The yield of ClO.2 in irradiated aqueous solutions of NaClO2 has been determined by pulse and steady-state radiolyses. The yield was found to be dependent on ClO–2 concentration but independent of pH. The solvated electron was found to react with ClO–2 with a rate constant (2.5 ± 0.5)× 109 S–1 mol–1 dm3 to yield ClO–. In its reaction with ClO–2 the OH. radical was found to produce two species; ClO.2 and an OH. adduct. At sufficiently high ClO–2 concentrations the adduct reacts with ClO–2 producing further ClO.2.