A single pulse shock tube has been used to study the pyrolysis of a hydrogenated sulphur compound, tetrahydrothiophene over the temperature range 1686-1885 K and pressures between 2.4 and 3.5 bars. Product yield and composition was determined using capillary column gas-chromatography with flame ionization detection and flame photometric sulphur selective detection. The principal hydrocarbon products at all temperatures were C2H4 and C2H2. Other hydrocarbon reaction products were CH4, C2H6, C3H4, C3H6, C4H3, C4H6, C4H10, C4H4, C6H6, C4H2 and some traces Of C-5 and C6H5 species. The sulphur compounds identified were hydrogen sulphide, carbon disulphide, thiophene and traces of ethyl mercapton. The pyrolysis experiments indicated that at lower temperatures the hydrogenated thiophene molecule reacts in two unimolecular channels to form C2H4+(CH2)2-S in the major faster channel which may be the route for other products. However, a second lower route may be the formation of C3H6+CH2S. The rate constant obtained for tetrahydrothiophene pyrolysis calculated for this study was k(dis(C4H8S)) = 1.26 x 10(13) exp (316.9 kJ mol(-1)) s(-1). Copyright (C) 2004 John Wiley Sons, Ltd.