Abstract Rate constants have been determined for the reactions of SO 4 − with a series of alcohols, including hydrated formaldehyde. The SO 4 − radical was produced by the laser‐flash photolysis of persulfate, S 2 O 8 2− . Rate constants for the reactions of SO 4 − with alcohols range from 1.0 × 10 7 for methanol to 3.4 × 10 8 M −1 s −1 for 1‐octanol. Rate constants for the reactions of SO 4 − with deuterated methanol and ethanol are lower by about a factor of 2.5. For methanol, ethanol, and 2‐propanol, the temperature dependence of the rate constant was determined over the range 10–45°C.