Two reactions of atmospheric importance involving the HS radical have been studied by using a discharge flow laser magnetic resonance technique: (1) HS + NO2 → products; and (2) HS + O2 → products. The rate constant for reaction 1 was measured at low pressure (∼1 Torr) between 221 and 415 K and a negative temperature dependence was observed: k1 = (2.9 ± 05) × 10-11 exp((240 ± 50)/T) cm3 molecule-1 s-1. The room temperature value for k1 from this study is higher than three previous values. Secondary chemistry associated with high H2S concentrations in the earlier studies is believed to contribute to the discrepancies. DS was used to investigate the isotope effect for reaction 1 and no evidence has been observed for a primary isotope effect, k(DS + NO2) = (7.3 ± 1.1) × 10-11 cm3 molecule-1 s-1, at 299 K. No reaction was observed with O2 and an upper limit of 1.5 × 10-17 cm3 molecule-1 s-1 was assigned to reaction 2.