The features of combination and scavenging reactions of OH radicals were experimentally investigated in comparison with the decomposition of water by the action of anodic microdischarges on an electrolytic cathode. The assumption was proved that the formation of primary water degradation products occurs mainly in the liquid phase in tracks of fast particles entering the solution from the discharge plasma. The local concentration of OH radicals in tracks was estimated at the level of 10–2 mol/l; although the peripheral regions of tracks can overlap because of the close arrangement of tracks in the near-discharge layer of the solution, the central regions of increased OH concentration may be considered as isolated.