The products of -radiation induced oxidation of p-hydroquinone (H2Q) solutions are p-quinone (Q), 2-hydroxybenzoquinone (2-Q-OH) and hydrogen peroxide (H2O2). The effects of dose, [O2], [H2Q], pH and different anions on yields have been investigated. Plots of G(Q) and G (H2O2) versus pH give titration type curves with pK of 1.2 and 1.3, respectively. This pK was attributed to protonation of the HO2 radical. The protonated form can oxidize H2Q. The neutral form of this radical appears to react with the semiquinone radical (HQ) to form (2-Q-OH) or disproportionate to give H2O2. A reaction mechanism is proposed to account for the experimental observations.