The reaction of H2S with atomic fluorine (1) has been studied in a discharge-flow system at 298 K to generate HS radicals for kinetic investigations. Mass spectrometric detection with single ion counting was employed. The rate constant k (1) was obtained from the rate of H2S consumption under the condition [HzS] 4 [Fl0 Radicals F + H2S + HF + HS, k(1) = (1.28 0.04). lo-'' cm3 s -' . Ber. Bunsenges. Phys. Chem. 91, 66-75 (1987) -0 VCH Verlagsgesellschaft mbH, D-6940 Weinheim, 1987.