X irradiation of single crystals of dibenzyl sulfone yields the PhCH2S·O2 radical while irradiation of PhSO2CH2COOH, PhSO2CH3, and PhSO2Ph yields the PhS·O2 radical. The principal values of the g and 33S hyperfine coupling tensors were measured (PhCH2S·O2: g=2.0027, 2.0056, 2.0094; A33S=96.3, 63.4, 56.2 G; PhS·O2: g=2.0023, 2.0051, 2.0072; A33S=107.1, 71.3, 71.3 G) and are discussed in terms of the electronic structure of these species. In PhSO2CH2COOH a further radical, g=1.89, 1.98, 2.04, is observed at low temperatures and is probably a trapped electron.