Wireless Sensors Networks (WSN) have recently been applied in a number of hazardous gas detectionapplications. The state-of-the-art works make an emphasis on sensing and delivering of alert messageover the WSN to an operator. Instead, in this paper, we propose a wireless sensor–actuator system whichaims at quick gas detection and immediate isolation of gas leak source. The low power wireless sensornode includes catalytic gas sensors, micro processing unit and wireless transceiver which communi-cates with wireless actuator using ZigBee/IEEE802.15.4 standard and BACnet protocol. Wireless actuatorconsists of power management circuit, micro processing unit and gas valve. The experimental resultsdemonstrate the sensor node long lifetime while fulfilling performance requirements, quick detection ofa hazardous gas and fast actuation time.