diff --git a/android/hal-ipc-api.txt b/android/hal-ipc-api.txt
index ba1b40a..aa5d730 100644
--- a/android/hal-ipc-api.txt
+++ b/android/hal-ipc-api.txt
@@ -1720,6 +1720,16 @@ Android HAL name: "gatt" (BT_PROFILE_GATT_ID)
 		In case of an error, the error response will be returned.
 
 	Opcode 0x1d - Add Characteristic command/response
+
+		Command parameters: Server (4 octets)
+		                    Service handle (4 octets)
+		                    UUID (16 octets)
+		                    Properties (4 octets)
+		                    Permissions (4 octets)
+		Response parameters: <none>
+
+		In case of an error, the error response will be returned.
+
 	Opcode 0x1e - Add Descriptor command/response
 	Opcode 0x1f - Start Service command/response
 	Opcode 0x20 - Stop Service command/response
diff --git a/android/hal-msg.h b/android/hal-msg.h
index 565976d..22ac058 100644
--- a/android/hal-msg.h
+++ b/android/hal-msg.h
@@ -740,6 +740,15 @@ struct hal_cmd_gatt_server_add_inc_service {
 	int32_t included_handle;
 } __attribute__((packed));
 
+#define HAL_OP_GATT_SERVER_ADD_CHARACTERISTIC	0x1d
+struct hal_cmd_gatt_server_add_characteristic {
+	int32_t server_if;
+	int32_t service_handle;
+	uint8_t uuid[16];
+	int32_t properties;
+	int32_t permissions;
+} __attribute__((packed));
+
 /* Notifications and confirmations */
 
 #define HAL_POWER_OFF			0x00