Abstract The ultraviolet absorption spectra of CH 3S and CH 2SH radicals have been measured between 215 and 380 nm using the pulse-radiolysis/kinetic-abso method. One absorption band between 250 and 300 nm and one around 215 nm have been tentatively assigned to the CH 2SH and CH 3S radicals, respectively. This spectrum has been used to measure the self-reaction rates of these radicals. Rate constants of 4 × 10 −11 and 7 × 10 −11 cm 3 molecule −1 s −1 have been measured at 298 K for CH 3S and CH 2SH recombination, respectively. The possible reaction pathways are discussed.