A gas chromatographic technique has been worked out which allows one to determine the kinetics of the formation and decomposition of sulfanes in the sulfur-hydrogen sulfide system at high temperature. Quantitative kinetic data are of great importance not only for research in that field but also for various practical applications like, for example, the sulfur deposition problem in sour gas reservoirs. Kinetic measurements have been carried out at different constant temperatures in the range of 120-270 degrees C in a chromatographic reactor, containing sulfur-coated glass beads and quartz powder, respectively. In order to determine the kinetic parameters, a numerical model of the gas chromatographic reactor has been developed. Based on the results obtained by fitting the experimental chromatograms to the model, a simplified reaction scheme is proposed. Preliminary results show that sulfane decomposition in the sulfur/H2S system is a rather slow reaction.