High concentrations of CO2 may develop particularly in the closed spaces during fires and can endanger the health of emergency personnel by causing serious physiological effects. The proposed prototype provides real-time continuous monitoring of CO2 in a wearable configuration sensing platform. A commercially available electrochemical CO2 sensor was selected due to its selectivity, sensitivity and low power demand. This was integrated onto an electronics platform that performed signal capture, processing and wireless communication, all within a compact, low-power, rugged enclosure. Wireless transmission (up to 1 km) of the sensor’s signal was achieved using a 2.4 GHz Zigbee module with an integrated ceramic antenna. The signal is currently received by a base station which is connected to a PC and monitored using HyperTerminal. The sensors are powered by a nickel metal hydride rechargeable battery which supplies power to the module for approximately 5 hours. The CO2 sensor is directly attached to the wireless module housed within the specially designed protective casing, and finally placed inside of the pocket on the boot of fire-fighter. Sensors are calibrated for CO2 concentrations ranging from atmospheric to 42000 ppm. The authors gratefully acknowledge the financial support of the European Union (Proetex FP6-2004-IST-4), the Centre for Bioanalytical Sciences (IDA-116294), and the CLARITY CSET (SFI-07/CE/I1147). Also, we thank to Diadora-Invicta Group (Italy) for providing the testing boot.