diff --git a/contrib/zmq/zmq_sub.py b/contrib/zmq/zmq_sub.py
index 7fbfbbd00..fa15f1285 100755
--- a/contrib/zmq/zmq_sub.py
+++ b/contrib/zmq/zmq_sub.py
@@ -16,11 +16,13 @@ zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"hashtx")
 zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"hashtxlock")
 zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"hashgovernancevote")
 zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"hashgovernanceobject")
+zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"hashinstantsenddoublespend")
 zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"rawblock")
 zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"rawtx")
 zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"rawtxlock")
 zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"rawgovernancevote")
 zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"rawgovernanceobject")
+zmqSubSocket.setsockopt(zmq.SUBSCRIBE, b"rawinstantsenddoublespend")
 zmqSubSocket.connect("tcp://127.0.0.1:%i" % port)
 
 try:
@@ -52,6 +54,9 @@ try:
         elif topic == "rawtxlock":
             print('- RAW TX LOCK ('+sequence+') -')
             print(binascii.hexlify(body).decode("utf-8"))
+        elif topic == "rawinstantsenddoublespend":
+            print('- RAW IS DOUBLE SPEND ('+sequence+') -')
+            print(binascii.hexlify(body).decode("utf-8"))
         elif topic == "hashgovernancevote":
             print('- HASH GOVERNANCE VOTE ('+sequence+') -')
             print(binascii.hexlify(body).decode("utf-8"))
@@ -64,7 +69,9 @@ try:
         elif topic == "rawgovernanceobject":
             print('- RAW GOVERNANCE OBJECT ('+sequence+') -')
             print(binascii.hexlify(body).decode("utf-8"))
-
+        elif topic == "hashinstantsenddoublespend":
+            print('- HASH IS DOUBLE SPEND ('+sequence+') -')
+            print(binascii.hexlify(body).decode("utf-8"))
 
 except KeyboardInterrupt:
     zmqContext.destroy()
diff --git a/doc/zmq.md b/doc/zmq.md
index 489ab549a..627f46c2d 100644
--- a/doc/zmq.md
+++ b/doc/zmq.md
@@ -66,6 +66,8 @@ Currently, the following notifications are supported:
     -zmqpubhashgovernanceobject=address
     -zmqpubrawgovernancevote=address
     -zmqpubhashgovernanceobject=address
+    -zmqpubrawinstantsenddoublespend=address
+    -zmqpubhashinstantsenddoublespend=address
 
 The socket type is PUB and the address must be a valid ZeroMQ socket
 address. The same address can be used in more than one notification.
diff --git a/src/init.cpp b/src/init.cpp
index c66e0039d..6d5d7c235 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -508,9 +508,11 @@ std::string HelpMessage(HelpMessageMode mode)
     strUsage += HelpMessageOpt("-zmqpubhashtxlock=<address>", _("Enable publish hash transaction (locked via InstantSend) in <address>"));
     strUsage += HelpMessageOpt("-zmqpubhashgovernancevote=<address>", _("Enable publish hash of governance votes in <address>"));
     strUsage += HelpMessageOpt("-zmqpubhashgovernanceobject=<address>", _("Enable publish hash of governance objects (like proposals) in <address>"));
+    strUsage += HelpMessageOpt("-zmqpubhashinstantsenddoublespend=<address>", _("Enable publish transaction hashes of attempted InstantSend double spend in <address>"));
     strUsage += HelpMessageOpt("-zmqpubrawblock=<address>", _("Enable publish raw block in <address>"));
     strUsage += HelpMessageOpt("-zmqpubrawtx=<address>", _("Enable publish raw transaction in <address>"));
     strUsage += HelpMessageOpt("-zmqpubrawtxlock=<address>", _("Enable publish raw transaction (locked via InstantSend) in <address>"));
+    strUsage += HelpMessageOpt("-zmqpubrawinstantsenddoublespend=<address>", _("Enable publish raw transactions of attempted InstantSend double spend in <address>"));
 #endif
 
     strUsage += HelpMessageGroup(_("Debugging/Testing options:"));
diff --git a/src/instantx.cpp b/src/instantx.cpp
index dc5431684..79412272b 100644
--- a/src/instantx.cpp
+++ b/src/instantx.cpp
@@ -117,7 +117,13 @@ bool CInstantSend::ProcessTxLockRequest(const CTxLockRequest& txLockRequest, CCo
                 if(hash != txLockRequest.GetHash()) {
                     LogPrint("instantsend", "CInstantSend::ProcessTxLockRequest -- Double spend attempt! %s\n", txin.prevout.ToStringShort());
                     // do not fail here, let it go and see which one will get the votes to be locked
-                    // TODO: notify zmq+script
+                    // NOTIFY ZMQ
+                    CTransaction txCurrent = *txLockRequest.tx; // currently processed tx
+                    auto itPrevious = mapTxLockCandidates.find(hash);
+                    if (itPrevious != mapTxLockCandidates.end() && itPrevious->second.txLockRequest) {
+                        CTransaction txPrevious = *itPrevious->second.txLockRequest.tx; // previously locked one
+                        GetMainSignals().NotifyInstantSendDoubleSpendAttempt(txCurrent, txPrevious);
+                    }
                 }
             }
         }
diff --git a/src/validationinterface.cpp b/src/validationinterface.cpp
index 436cedf10..26b08647d 100644
--- a/src/validationinterface.cpp
+++ b/src/validationinterface.cpp
@@ -28,6 +28,7 @@ void RegisterValidationInterface(CValidationInterface* pwalletIn) {
     g_signals.NewPoWValidBlock.connect(boost::bind(&CValidationInterface::NewPoWValidBlock, pwalletIn, _1, _2));
     g_signals.NotifyGovernanceObject.connect(boost::bind(&CValidationInterface::NotifyGovernanceObject, pwalletIn, _1));
     g_signals.NotifyGovernanceVote.connect(boost::bind(&CValidationInterface::NotifyGovernanceVote, pwalletIn, _1));
+    g_signals.NotifyInstantSendDoubleSpendAttempt.connect(boost::bind(&CValidationInterface::NotifyInstantSendDoubleSpendAttempt, pwalletIn, _1, _2));
 }
 
 void UnregisterValidationInterface(CValidationInterface* pwalletIn) {
@@ -46,6 +47,7 @@ void UnregisterValidationInterface(CValidationInterface* pwalletIn) {
     g_signals.AcceptedBlockHeader.disconnect(boost::bind(&CValidationInterface::AcceptedBlockHeader, pwalletIn, _1));
     g_signals.NotifyGovernanceObject.disconnect(boost::bind(&CValidationInterface::NotifyGovernanceObject, pwalletIn, _1));
     g_signals.NotifyGovernanceVote.disconnect(boost::bind(&CValidationInterface::NotifyGovernanceVote, pwalletIn, _1));
+    g_signals.NotifyInstantSendDoubleSpendAttempt.disconnect(boost::bind(&CValidationInterface::NotifyInstantSendDoubleSpendAttempt, pwalletIn, _1, _2));
 }
 
 void UnregisterAllValidationInterfaces() {
@@ -64,4 +66,5 @@ void UnregisterAllValidationInterfaces() {
     g_signals.AcceptedBlockHeader.disconnect_all_slots();
     g_signals.NotifyGovernanceObject.disconnect_all_slots();
     g_signals.NotifyGovernanceVote.disconnect_all_slots();
+    g_signals.NotifyInstantSendDoubleSpendAttempt.disconnect_all_slots();
 }
diff --git a/src/validationinterface.h b/src/validationinterface.h
index 8ce15b30c..f5f5df31c 100644
--- a/src/validationinterface.h
+++ b/src/validationinterface.h
@@ -40,6 +40,7 @@ protected:
     virtual void NotifyTransactionLock(const CTransaction &tx) {}
     virtual void NotifyGovernanceVote(const CGovernanceVote &vote) {}
     virtual void NotifyGovernanceObject(const CGovernanceObject &object) {}
+    virtual void NotifyInstantSendDoubleSpendAttempt(const CTransaction &currentTx, const CTransaction &previousTx) {}
     virtual void SetBestChain(const CBlockLocator &locator) {}
     virtual bool UpdatedTransaction(const uint256 &hash) { return false;}
     virtual void Inventory(const uint256 &hash) {}
@@ -77,6 +78,8 @@ struct CMainSignals {
     boost::signals2::signal<void (const CGovernanceVote &)> NotifyGovernanceVote;
     /** Notifies listeners of a new governance object. */
     boost::signals2::signal<void (const CGovernanceObject &)> NotifyGovernanceObject;
+    /** Notifies listeners of a attempted InstantSend double spend*/
+    boost::signals2::signal<void(const CTransaction &currentTx, const CTransaction &previousTx)> NotifyInstantSendDoubleSpendAttempt;
     /** Notifies listeners of an updated transaction without new data (for now: a coinbase potentially becoming visible). */
     boost::signals2::signal<bool (const uint256 &)> UpdatedTransaction;
     /** Notifies listeners of a new active block chain. */
diff --git a/src/zmq/zmqabstractnotifier.cpp b/src/zmq/zmqabstractnotifier.cpp
index ea993d606..6e280eefe 100644
--- a/src/zmq/zmqabstractnotifier.cpp
+++ b/src/zmq/zmqabstractnotifier.cpp
@@ -35,3 +35,8 @@ bool CZMQAbstractNotifier::NotifyGovernanceObject(const CGovernanceObject& /*obj
 {
     return true;
 }
+
+bool CZMQAbstractNotifier::NotifyInstantSendDoubleSpendAttempt(const CTransaction& /*currentTx*/, const CTransaction& /*previousTx*/)
+{
+    return true;
+}
diff --git a/src/zmq/zmqabstractnotifier.h b/src/zmq/zmqabstractnotifier.h
index ee6aa3ad7..6ce9d1253 100644
--- a/src/zmq/zmqabstractnotifier.h
+++ b/src/zmq/zmqabstractnotifier.h
@@ -39,6 +39,7 @@ public:
     virtual bool NotifyTransactionLock(const CTransaction &transaction);
     virtual bool NotifyGovernanceVote(const CGovernanceVote &vote);
     virtual bool NotifyGovernanceObject(const CGovernanceObject &object);
+    virtual bool NotifyInstantSendDoubleSpendAttempt(const CTransaction &currentTx, const CTransaction &previousTx);
 
 
 protected:
diff --git a/src/zmq/zmqconfig.h b/src/zmq/zmqconfig.h
index b7168c962..c1a8e6c3f 100644
--- a/src/zmq/zmqconfig.h
+++ b/src/zmq/zmqconfig.h
@@ -22,6 +22,8 @@
 #include "governance-object.h"
 #include "governance-vote.h"
 
+#include "instantx.h"
+
 void zmqError(const char *str);
 
 #endif // BITCOIN_ZMQ_ZMQCONFIG_H
diff --git a/src/zmq/zmqnotificationinterface.cpp b/src/zmq/zmqnotificationinterface.cpp
index 7895f17aa..8a15fd1a9 100644
--- a/src/zmq/zmqnotificationinterface.cpp
+++ b/src/zmq/zmqnotificationinterface.cpp
@@ -40,11 +40,13 @@ CZMQNotificationInterface* CZMQNotificationInterface::Create()
     factories["pubhashtxlock"] = CZMQAbstractNotifier::Create<CZMQPublishHashTransactionLockNotifier>;
     factories["pubhashgovernancevote"] = CZMQAbstractNotifier::Create<CZMQPublishHashGovernanceVoteNotifier>;
     factories["pubhashgovernanceobject"] = CZMQAbstractNotifier::Create<CZMQPublishHashGovernanceObjectNotifier>;
+    factories["pubhashinstantsenddoublespend"] = CZMQAbstractNotifier::Create<CZMQPublishHashInstantSendDoubleSpendNotifier>;
     factories["pubrawblock"] = CZMQAbstractNotifier::Create<CZMQPublishRawBlockNotifier>;
     factories["pubrawtx"] = CZMQAbstractNotifier::Create<CZMQPublishRawTransactionNotifier>;
     factories["pubrawtxlock"] = CZMQAbstractNotifier::Create<CZMQPublishRawTransactionLockNotifier>;
     factories["pubrawgovernancevote"] = CZMQAbstractNotifier::Create<CZMQPublishRawGovernanceVoteNotifier>;
     factories["pubrawgovernanceobject"] = CZMQAbstractNotifier::Create<CZMQPublishRawGovernanceObjectNotifier>;
+    factories["pubrawinstantsenddoublespend"] = CZMQAbstractNotifier::Create<CZMQPublishRawInstantSendDoubleSpendNotifier>;
 
     for (std::map<std::string, CZMQNotifierFactory>::const_iterator i=factories.begin(); i!=factories.end(); ++i)
     {
@@ -217,3 +219,16 @@ void CZMQNotificationInterface::NotifyGovernanceObject(const CGovernanceObject &
         }
     }
 }
+
+void CZMQNotificationInterface::NotifyInstantSendDoubleSpendAttempt(const CTransaction &currentTx, const CTransaction &previousTx)
+{
+    for (auto it = notifiers.begin(); it != notifiers.end();) {
+        CZMQAbstractNotifier *notifier = *it;
+        if (notifier->NotifyInstantSendDoubleSpendAttempt(currentTx, previousTx)) {
+            ++it;
+        } else {
+            notifier->Shutdown();
+            it = notifiers.erase(it);
+        }
+    }
+}
diff --git a/src/zmq/zmqnotificationinterface.h b/src/zmq/zmqnotificationinterface.h
index aeaed254a..f552751e9 100644
--- a/src/zmq/zmqnotificationinterface.h
+++ b/src/zmq/zmqnotificationinterface.h
@@ -29,6 +29,7 @@ protected:
     void NotifyTransactionLock(const CTransaction &tx) override;
     void NotifyGovernanceVote(const CGovernanceVote& vote) override;
     void NotifyGovernanceObject(const CGovernanceObject& object) override;
+    void NotifyInstantSendDoubleSpendAttempt(const CTransaction &currentTx, const CTransaction &previousTx) override;
 
 
 private:
diff --git a/src/zmq/zmqpublishnotifier.cpp b/src/zmq/zmqpublishnotifier.cpp
index 8a6c4167d..9f46331c0 100644
--- a/src/zmq/zmqpublishnotifier.cpp
+++ b/src/zmq/zmqpublishnotifier.cpp
@@ -15,11 +15,13 @@ static const char *MSG_HASHTX     = "hashtx";
 static const char *MSG_HASHTXLOCK = "hashtxlock";
 static const char *MSG_HASHGVOTE  = "hashgovernancevote";
 static const char *MSG_HASHGOBJ   = "hashgovernanceobject";
+static const char *MSG_HASHISCON  = "hashinstantsenddoublespend";
 static const char *MSG_RAWBLOCK   = "rawblock";
 static const char *MSG_RAWTX      = "rawtx";
 static const char *MSG_RAWTXLOCK  = "rawtxlock";
 static const char *MSG_RAWGVOTE   = "rawgovernancevote";
 static const char *MSG_RAWGOBJ    = "rawgovernanceobject";
+static const char *MSG_RAWISCON   = "rawinstantsenddoublespend";
 
 // Internal function to send multipart message
 static int zmq_send_multipart(void *sock, const void* data, size_t size, ...)
@@ -197,6 +199,20 @@ bool CZMQPublishHashGovernanceObjectNotifier::NotifyGovernanceObject(const CGove
     return SendMessage(MSG_HASHGOBJ, data, 32);
 }
 
+bool CZMQPublishHashInstantSendDoubleSpendNotifier::NotifyInstantSendDoubleSpendAttempt(const CTransaction &currentTx, const CTransaction &previousTx)
+{
+    uint256 currentHash = currentTx.GetHash(), previousHash = previousTx.GetHash();
+    LogPrint("zmq", "zmq: Publish hashinstantsenddoublespend %s conflicts against %s\n", currentHash.ToString(), previousHash.ToString());
+    char dataCurrentHash[32], dataPreviousHash[32];
+    for (unsigned int i = 0; i < 32; i++) {
+        dataCurrentHash[31 - i] = currentHash.begin()[i];
+        dataPreviousHash[31 - i] = previousHash.begin()[i];
+    }
+    return SendMessage(MSG_HASHISCON, dataCurrentHash, 32)
+        && SendMessage(MSG_HASHISCON, dataPreviousHash, 32);
+}
+
+
 bool CZMQPublishRawBlockNotifier::NotifyBlock(const CBlockIndex *pindex)
 {
     LogPrint("zmq", "zmq: Publish rawblock %s\n", pindex->GetBlockHash().GetHex());
@@ -253,3 +269,13 @@ bool CZMQPublishRawGovernanceObjectNotifier::NotifyGovernanceObject(const CGover
     ss << govobj;
     return SendMessage(MSG_RAWGOBJ, &(*ss.begin()), ss.size());
 }
+
+bool CZMQPublishRawInstantSendDoubleSpendNotifier::NotifyInstantSendDoubleSpendAttempt(const CTransaction &currentTx, const CTransaction &previousTx)
+{
+    LogPrint("zmq", "zmq: Publish rawinstantsenddoublespend %s conflicts with %s\n", currentTx.GetHash().ToString(), previousTx.GetHash().ToString());
+    CDataStream ssCurrent(SER_NETWORK, PROTOCOL_VERSION), ssPrevious(SER_NETWORK, PROTOCOL_VERSION);
+    ssCurrent << currentTx;
+    ssPrevious << previousTx;
+    return SendMessage(MSG_RAWISCON, &(*ssCurrent.begin()), ssCurrent.size())
+        && SendMessage(MSG_RAWISCON, &(*ssPrevious.begin()), ssPrevious.size());
+}
diff --git a/src/zmq/zmqpublishnotifier.h b/src/zmq/zmqpublishnotifier.h
index 31c90317d..e51b6a314 100644
--- a/src/zmq/zmqpublishnotifier.h
+++ b/src/zmq/zmqpublishnotifier.h
@@ -60,6 +60,12 @@ public:
     bool NotifyGovernanceObject(const CGovernanceObject &object) override;
 };
 
+class CZMQPublishHashInstantSendDoubleSpendNotifier : public CZMQAbstractPublishNotifier
+{
+public:
+    bool NotifyInstantSendDoubleSpendAttempt(const CTransaction &currentTx, const CTransaction &previousTx) override;
+};
+
 class CZMQPublishRawBlockNotifier : public CZMQAbstractPublishNotifier
 {
 public:
@@ -89,4 +95,10 @@ class CZMQPublishRawGovernanceObjectNotifier : public CZMQAbstractPublishNotifie
 public:
     bool NotifyGovernanceObject(const CGovernanceObject &object) override;
 };
+
+class CZMQPublishRawInstantSendDoubleSpendNotifier : public CZMQAbstractPublishNotifier
+{
+public:
+    bool NotifyInstantSendDoubleSpendAttempt(const CTransaction &currentTx, const CTransaction &previousTx) override;
+};
 #endif // BITCOIN_ZMQ_ZMQPUBLISHNOTIFIER_H