diff --git a/README.md b/README.md
index 920f130..2f77305 100644
--- a/README.md
+++ b/README.md
@@ -1,13 +1,15 @@
 [![Build Status](https://travis-ci.org/grillbaer/esp32-geiger-counter.svg?branch=master)](https://travis-ci.org/grillbaer/esp32-geiger-counter)
 
-# IoT Geiger Counter with ESP32, OLED Display and Thingspeak Channel
+# IoT Geiger Counter with ESP32, OLED Display, Thingspeak Channel and MQTT
 
 - Measures radioactive gamma and beta radiation with quite good resolution at the typical low levels of the natural radiation (due to the big STS-6 tube)
 - Displays the current counts per minute (CPM), estimated dose equivalent rate in micro-Sievert per hour (µS/h) and 10 minutes history with 5 second resolution as bargraph
 ![Circuit Board](media/geiger-counter-pcb.jpg)
 - Low-power mode for use with batteries, OLED display and click sounds on, WiFi off
-- WiFi mode for thingspeak data upload every minute, see https://thingspeak.com/channels/758223
+- WiFi mode for
+  - optional thingspeak data upload every minute, see https://thingspeak.com/channels/758223
 [![https://thingspeak.com/channels/758223](media/thingspeak.png)](https://thingspeak.com/channels/758223)
+  - MQTT publishing to a broker every minute
 
 Feel free to use this project as a base for your own projects AT YOUR OWN RISK!
 
@@ -25,10 +27,22 @@ Feel free to use this project as a base for your own projects AT YOUR OWN RISK!
 
 # Software
 
-- [PlatformIO VSCode project](https://github.com/platformio/platformio-vscode-ide) using [Arduino](https://github.com/arduino/Arduino) library, [Espressif ESP-IDF](https://github.com/espressif/esp-idf) for sleep functions and [U8g2](https://github.com/olikraus/u8g2) for display output
+- [PlatformIO VSCode project](https://github.com/platformio/platformio-vscode-ide) using [Arduino](https://github.com/arduino/Arduino) library, [Espressif ESP-IDF](https://github.com/espressif/esp-idf) for sleep functions, [U8g2](https://github.com/olikraus/u8g2) for display output and [Arduino-MQTT](https://github.com/256dpi/arduino-mqtt).
 - Low-power mode uses light sleep, a wake-up for each signal pulse change and a wake-up every 1000 ms to update pulse statistics and OLED. This results in about 90% sleep. Could be improved using deep sleep and ULP. However, light sleep is already quite good and much easier.
 - WiFi mode uses no sleep and simple interrupts for pulse counting. Pulse statistics and OLED are updated every 1000 ms, data is sent to thingspeak every 60 s.
-- Credentials (WiFi SSID, password, thingspeak channel key) are declared in `credentials.h` and replaced by dummy values in `credentials.cpp` by default. Define your real secrets in a sibling file named `secret_credentials.h` (which is never committed!). It will automatically be included by `credentials.cpp` if it exists.
+- Credentials, addresses and user for WiFi, thingspeak channel and mqtt broker are declared in `credentials.h` and replaced by dummy values in `credentials.cpp` by default. Define your real secrets in a sibling file named `secret_credentials.h` (do never committed!). It will automatically be included by `credentials.cpp` if it exists. You may copy `TEMPLATE_secret_credentials.h` as a starting point.
+
+# MQTT Message Format
+
+Published messages have the following JSON format:
+```json
+{
+  "pulses": 69,
+  "cpm": 69,
+  "uSph": 0.08,
+  "secs": 60
+}
+```
 
 # Geiger Tube Pulse Forming
 
diff --git a/include/credentials.h b/include/credentials.h
index 863cd21..f8c67c9 100644
--- a/include/credentials.h
+++ b/include/credentials.h
@@ -5,4 +5,10 @@ extern const char *wifiSsid;
 extern const char *wifiPassword;
 extern const char *thingspeakApiKey;
 
+extern const char *mqttHost;
+extern int mqttPort;
+extern const char *mqttUser;
+extern const char *mqttPassword;
+extern const char *mqttTopic;
+
 #endif /* CREDENTIALS_H_ */
diff --git a/include/ingest.h b/include/ingest.h
index f598e58..cc4a371 100644
--- a/include/ingest.h
+++ b/include/ingest.h
@@ -5,6 +5,7 @@
 
 void initIngest();
 void deinitIngest();
-void ingest(GeigerData &geigerData, uint16_t intervalSamples);
+void ingestToThingspeak(GeigerData &geigerData, uint16_t intervalSamples);
+void ingestToMqtt(GeigerData &geigerData, uint16_t intervalSamples);
 
 #endif /* INGEST_H_ */
diff --git a/platformio.ini b/platformio.ini
index 1752423..5750141 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -12,7 +12,7 @@
 platform = espressif32
 board = lolin32
 framework = arduino
-
 monitor_speed = 115200
-
-lib_deps = U8g2@2.26.1
\ No newline at end of file
+lib_deps = 
+	U8g2@2.26.1
+	256dpi/MQTT@^2.4.7
diff --git a/src/TEMPLATE_secret_credentials.h b/src/TEMPLATE_secret_credentials.h
new file mode 100644
index 0000000..2f2f958
--- /dev/null
+++ b/src/TEMPLATE_secret_credentials.h
@@ -0,0 +1,25 @@
+#define _SECRET_CREDENTIALS
+
+// Copy this file to secret_credentials.h and adjust for
+// your needs and environment.
+
+// !!! NEVER COMMIT YOUR SECRETS !!!
+
+const char *wifiSsid = "MyWiFi";
+const char *wifiPassword = "mypassword";
+
+
+// ThingsPeak Channel
+
+// set key to NULL or empty string to disable ThingsPeak ingest:
+const char *thingspeakApiKey = "MYAPIKEY";
+
+
+// MQTT Broker
+
+// set host to NULL or empty string to disable MQTT publishing:
+const char *mqttHost = "my.mqtt.server";
+int mqttPort = 1833;
+const char *mqttUser = "user";
+const char *mqttPassword = "mypassword";
+const char *mqttTopic = "home/radioactivity";
diff --git a/src/credentials.cpp b/src/credentials.cpp
index 1f63e3d..7e15988 100644
--- a/src/credentials.cpp
+++ b/src/credentials.cpp
@@ -10,6 +10,12 @@
 // use dummy credentials to make it compilable without secrets
 const char *wifiSsid = "unset-wifi-ssid";
 const char *wifiPassword = "unset-password";
-const char *thingspeakApiKey = "unset-thinkspeak-api-key";
+const char *thingspeakApiKey = ""; // empty to disable thinkspeak
+
+const char *mqttHost = ""; // empty to disable MQTT
+int mqttPort = 1833;
+const char *mqttUser = "user";
+const char *mqttPassword = "unset-password";
+const char *mqttTopic = "home/geiger/radioactivity";
 
 #endif
diff --git a/src/ingest.cpp b/src/ingest.cpp
index 42d6f99..7590e35 100644
--- a/src/ingest.cpp
+++ b/src/ingest.cpp
@@ -1,4 +1,5 @@
 #include <WiFi.h>
+#include <MQTT.h>
 
 #include "GeigerData.h"
 
@@ -6,10 +7,13 @@
 
 const char *thingsPeakUrl = "api.thingspeak.com";
 
-bool connect()
+WiFiClient mqttWifiClient;
+MQTTClient mqttClient;
+
+bool connectWiFi()
 {
-	uint16_t retries = 3;
-	while (WiFi.status() != WL_CONNECTED && (--retries) > 0)
+	uint16_t retries = 10;
+	while (WiFi.status() != WL_CONNECTED && (retries--) > 0)
 	{
 		Serial.print("Trying to connect to ");
 		Serial.print(wifiSsid);
@@ -35,7 +39,7 @@ bool connect()
 	return WiFi.status() == WL_CONNECTED;
 }
 
-void disconnect()
+void disconnectWiFi()
 {
 	Serial.println("Disconnecting WiFi");
 	WiFi.disconnect(true, true);
@@ -43,20 +47,23 @@ void disconnect()
 
 void initIngest()
 {
-	connect();
+	connectWiFi();
 }
 
 void deinitIngest()
 {
 	if (WiFi.status() == WL_CONNECTED)
 	{
-		disconnect();
+		disconnectWiFi();
 	}
 }
 
-void ingest(GeigerData &geigerData, uint16_t intervalSamples)
+void ingestToThingspeak(GeigerData &geigerData, uint16_t intervalSamples)
 {
-	if (!connect())
+	if (!connectWiFi())
+		return;
+
+	if (thingsPeakUrl == NULL || thingsPeakUrl[0] == 0)
 		return;
 
 	WiFiClient client;
@@ -66,7 +73,7 @@ void ingest(GeigerData &geigerData, uint16_t intervalSamples)
 		Serial.print(thingsPeakUrl);
 		Serial.println(" failed");
 		// disconnect from WiFi to trigger fresh connect on next ingest
-		disconnect();
+		disconnectWiFi();
 	}
 	else
 	{
@@ -123,3 +130,58 @@ void ingest(GeigerData &geigerData, uint16_t intervalSamples)
 		client.stop();
 	}
 }
+
+bool connectMqtt()
+{
+	if (!connectWiFi())
+		return false;
+
+	if (mqttHost == NULL || mqttHost[0] == 0)
+		return false;
+
+	if (!mqttClient.connected())
+	{
+		Serial.print("Connecting to MQTT host ");
+		Serial.print(mqttHost);
+		Serial.print(":");
+		Serial.print(mqttPort);
+		Serial.print(" user ");
+		Serial.print(mqttUser);
+		mqttClient.begin(mqttHost, mqttPort, mqttWifiClient);
+		if (mqttClient.connect("esp32-geiger-counter", mqttUser, mqttPassword))
+		{
+			Serial.println(" successful");
+		}
+		else
+		{
+			Serial.println(" failed");
+			// disconnect from WiFi to trigger fresh connect on next ingest
+			disconnectWiFi();
+			return false;
+		}
+	}
+
+	return true;
+}
+
+void disconnectMqtt()
+{
+	mqttClient.disconnect();
+}
+
+void ingestToMqtt(GeigerData &geigerData, uint16_t intervalSamples)
+{
+	if (connectMqtt())
+	{
+		const unsigned long pulses = geigerData.getPreviousPulses(1,
+																  intervalSamples);
+		const unsigned long cpm = (unsigned long)(pulses / ((float)intervalSamples * geigerData.sampleSeconds / 60.) + 0.5);
+		const float uSph = geigerData.toMicroSievertPerHour(pulses,
+															intervalSamples);
+		char payload[129];
+		sprintf(payload, "{\"pulses\":%lu, \"cpm\":%lu,\"uSph\":%.2f,\"secs\":%d}",
+				pulses, cpm, uSph, (int)intervalSamples);
+
+		mqttClient.publish(mqttTopic, payload);
+	}
+}
diff --git a/src/main.cpp b/src/main.cpp
index 6863042..1ab2cb7 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -97,7 +97,8 @@ void loop()
 		if (ingestCountdown <= 0)
 		{
 			ingestCountdown = ingestInterval;
-			ingest(geigerData, ingestInterval);
+			ingestToThingspeak(geigerData, ingestInterval);
+			ingestToMqtt(geigerData, ingestInterval);
 		}
 	}
 	else