diff --git a/protob/Makefile b/protob/Makefile
index 4168b783a..74d2e3339 100644
--- a/protob/Makefile
+++ b/protob/Makefile
@@ -1,4 +1,4 @@
-check: messages.pb messages-bitcoin.pb messages-bootloader.pb messages-cardano.pb messages-common.pb messages-crypto.pb messages-debug.pb messages-ethereum.pb messages-lisk.pb messages-management.pb messages-monero.pb messages-nem.pb messages-ripple.pb messages-stellar.pb messages-tezos.pb
+check: messages.pb messages-bitcoin.pb messages-bootloader.pb messages-cardano.pb messages-common.pb messages-crypto.pb messages-debug.pb messages-ethereum.pb messages-lisk.pb messages-management.pb messages-monero.pb messages-nem.pb messages-ripple.pb messages-stellar.pb messages-tezos.pb messages-ontology.pb
 
 %.pb: %.proto
 	protoc -I/usr/include -I. $< -o $@
diff --git a/protob/messages-ontology.proto b/protob/messages-ontology.proto
new file mode 100644
index 000000000..338d5ce38
--- /dev/null
+++ b/protob/messages-ontology.proto
@@ -0,0 +1,198 @@
+syntax = "proto2";
+
+// Sugar for easier handling in Java
+option java_package = "com.satoshilabs.trezor.lib.protobuf";
+option java_outer_classname = "TrezorMessageOntology";
+
+/**
+* Ontology Transaction
+*/
+message OntologyTransaction {
+
+    /**
+    * Attribute of Ontology transaction
+    */
+    message OntologyTxAttribute {
+        optional uint32 usage = 1;
+        optional bytes data = 2;
+    }
+
+    optional uint32 version = 1;
+    optional uint32 type = 2;
+    optional uint32 nonce = 3;
+    optional uint64 gas_price = 4;
+    optional uint64 gas_limit = 5;
+    optional string payer = 6;
+    repeated OntologyTxAttribute tx_attributes = 7;
+}
+
+/**
+ * Request: Ask device for Ontology public key corresponding to address_n path
+ * @start
+ * @next OntologyPublicKey
+*/
+message OntologyGetPublicKey {
+    repeated uint32 address_n = 1;  // BIP-32 path to derive the key from master node
+    optional bool show_display = 2; // Optionally show on display before sending the result
+}
+
+/**
+ * Response: Contains Ontology public key derived from device private seed
+ * @end
+*/
+message OntologyPublicKey {
+    optional bytes public_key = 1;  // Ontology public key
+}
+
+/**
+ * Request: Ask device for Ontology address corresponding to address_n path
+ * @start
+ * @next OntologyAddress
+ */
+message OntologyGetAddress {
+    repeated uint32 address_n = 1;  // BIP-32 path to derive the key from master node
+    optional bool show_display = 2; // Optionally show on display before sending the result
+}
+
+/**
+ * Response: Contains Ontology address derived from device private seed
+ * @end
+ */
+message OntologyAddress {
+    optional string address = 1;    // Ontology address
+}
+
+
+/**
+ * Request: Ask device to sign Ontology transfer
+ * @start
+ * @next OntologySignedTransfer
+ */
+ message OntologySignTransfer {
+    repeated uint32 address_n = 1;                  // BIP-32 path to derive the key from master node
+    optional OntologyTransaction transaction = 2;
+    optional OntologyTransfer transfer = 3;
+    
+    /**
+    * Ontology Transfer
+    */
+    message OntologyTransfer {
+        /**
+        * Ontology Asset
+        */
+        enum OntologyAsset {
+            ONT = 1;
+            ONG = 2;
+        }
+
+        optional OntologyAsset asset = 1;
+        optional uint64 amount = 2;
+        optional string from_address = 3;
+        optional string to_address = 4;
+    }
+}
+
+/**
+* Response: Contains Ontology transfer signature
+* @end
+*/
+message OntologySignedTransfer {
+    optional bytes signature = 1;
+    optional bytes payload = 2;
+}
+
+/**
+ * Request: Ask device to sign Ontology ONG withdrawal
+ * @start
+ * @next OntologySignedWithdrawOng
+ */
+ message OntologySignWithdrawOng {
+    repeated uint32 address_n = 1;                  // BIP-32 path to derive the key from master node
+    optional OntologyTransaction transaction = 2;
+    optional OntologyWithdrawOng withdraw_ong = 3;
+    
+    /**
+    * Ontology ONG Withdrawal
+    */
+    message OntologyWithdrawOng {
+        optional uint64 amount = 1;
+        optional string from_address = 2;
+        optional string to_address = 3;
+    }
+}
+
+/**
+* Response: Contains Ontology ONG withdrawal signature
+* @end
+*/
+message OntologySignedWithdrawOng {
+    optional bytes signature = 1;
+    optional bytes payload = 2;
+}
+
+/**
+ * Request: Ask device to sign Ontology ONT ID registration
+ * @start
+ * @next OntologySignedOntIdRegister
+ */
+ message OntologySignOntIdRegister {
+    repeated uint32 address_n = 1;                  // BIP-32 path to derive the key from master node
+    optional OntologyTransaction transaction = 2;
+    optional OntologyOntIdRegister ont_id_register = 3;
+
+    /**
+    * Ontology ONT ID registration
+    */
+    message OntologyOntIdRegister {
+        optional string ont_id = 1;
+        optional bytes public_key = 2;
+    }
+}
+
+/**
+* Response: Contains Ontology ONT ID registration signature
+* @end
+*/
+message OntologySignedOntIdRegister {
+    optional bytes signature = 1;
+    optional bytes payload = 2;
+}
+
+
+/**
+ * Request: Ask device to sign Ontology ONT ID attributes adding
+ * @start
+ * @next OntologySignedOntIdAddAttributes
+ */
+ message OntologySignOntIdAddAttributes {
+    repeated uint32 address_n = 1;                  // BIP-32 path to derive the key from master node
+    optional OntologyTransaction transaction = 2;
+    optional OntologyOntIdAddAttributes ont_id_add_attributes = 3;
+
+    /**
+    * Attribute of Ontology ONT ID
+    */
+    message OntologyOntIdAttribute {
+        optional string key = 1;
+        optional string type = 2;
+        optional string value = 3;
+    }
+
+    /**
+    * Ontology ONT ID attributes adding
+    */
+    message OntologyOntIdAddAttributes {
+        optional string ont_id = 1;
+        optional bytes public_key = 2;
+        repeated OntologyOntIdAttribute ont_id_attributes = 3;
+    }
+}
+
+/**
+* Response: Contains Ontology ONT ID attributes adding signature
+* @end
+*/
+message OntologySignedOntIdAddAttributes {
+    optional bytes signature = 1;
+    optional bytes payload = 2;
+}
diff --git a/protob/messages.proto b/protob/messages.proto
index ff5171f43..05536de10 100644
--- a/protob/messages.proto
+++ b/protob/messages.proto
@@ -174,6 +174,18 @@ enum MessageType {
     MessageType_CardanoTxAck = 309 [(wire_in) = true];
     MessageType_CardanoSignedTransaction = 310 [(wire_out) = true];
 
+    // Ontology
+    MessageType_OntologyGetAddress = 350 [(wire_in) = true];
+    MessageType_OntologyAddress = 351 [(wire_out) = true];
+    MessageType_OntologyGetPublicKey = 352 [(wire_in) = true];
+    MessageType_OntologyPublicKey = 353 [(wire_out) = true];
+    MessageType_OntologySignTx = 354 [(wire_in) = true];
+    MessageType_OntologySignedTx = 355 [(wire_out) = true];
+    MessageType_OntologySignTransfer = 356 [(wire_in) = true];
+    MessageType_OntologySignedTransfer = 357 [(wire_out) = true];
+    MessageType_OntologySignWithdrawOng = 358 [(wire_in) = true];
+    MessageType_OntologySignedWithdrawOng = 359 [(wire_out) = true];
+
     // Ripple
     MessageType_RippleGetAddress = 400 [(wire_in) = true];
     MessageType_RippleAddress = 401 [(wire_out) = true];