[en] On-line electrochemical sulphide analysers are in use at Heavy Water Project at Manuguru and Kota, for the purpose of continuous monitoring of H₂S in the utility streams. The performance of the electrochemical analysers has not been satisfactory in the lower range (0-1 ppm) of sulphide concentration and the electrodes of these analysers are found to be failing frequently. A simple gas liquid equilibration technique has been developed for monitoring the low concentration of sulphide in water. This paper describes the theoretical basis and experimental set-up followed by some of the results. It was observed that this technique can be readily adopted for detecting leakages of H₂S into utility streams arising from failures of heat exchanger tubes. (author). 6 figs