An environmentally friendly sulfide sensor based on the room-temperature phosphorescence (RTP) of the ZnO/SiO(2) nanocomposite has been developed. The ZnO/SiO(2) nanocomposite prepared by the sol-gel route produces highly emissive broadband RTP which can be clearly observed by the naked eye. The phosphorescence intensity monitored at 460 nm (excitation at 320 nm) decreases with increasing sulfide ions concentrations. The response behavior of the sensor is dependent on the pH value of the solution. At pH 10, the sensor shows a good, linear response to sulfide from 4.88 x 10(-5) to 1.02 x 10(-2) M with a detection limit of 1.64 x 10(-6) M (3sigma). It has been successfully applied to the determination of sulfide in spiked water and wastewater. Furthermore, this sensor can be regenerated by dipping it into an H(2)O(2) solution. The mechanisms for the RTP detection of sulfide based on the ZnO/SiO(2) nanocomposite and the sensor regeneration by H(2)O(2) are proposed.