The application of tert-butanol as an OH scavenger in aqueous, oxygenated solutions was studied by pulse radiolysis and computer simulation of the entire reaction mechanism. In such systems, the initially produced tert-butanol radical (. Rib) reacts with O2 with a rate constant ofk = 1.4. IO9.M-' s-'. The UV absorption-spectrum of the resulting tert-butanol peroxy-radical, . OORlb, was determined. The rate constant for its dimerization, 2 . OOR,,+ R,b04R,b, is k = 1.8. lo8 M-' s-'. The formation of H 0 2 from the decay of RlbO4RLb has often been neglected in earlier studies. Our reinvestigation showed a yield of 5 f 2%.In deoxygenated systems we confirmed the rate constant for . Rtb dimerization to be k = 6. lo8 M-' s-'.The UV spectrum o f . Rlb was determined to be slightly different from literature data.