Europa's surface is chemically altered by radiolysis from energetic charged particle bombardment. It has been suggested that hydrated sulfuric acid ([H.sub.2]S[O.sub.4] * n[H.sub.2]O) is a major surface species and is part of a radiolytic sulfur cycle, where a dynamic equilibrium exists between continuous production and destruction of sulfur polymers [S.sub.x], sulfur dioxide S[O.sub.2], hydrogen sulfide [H.sub.2]S, and [H.sub.2]S[O.sub.4] * n[H.sub.2]O. We measured the rate of sulfate anion production for cyclo-octal sulfur grains in frozen water at temperatures, energies, and close rates appropriate for Europa using energetic electrons. The measured rate is [G.sub.Mixture](S[O.sup.2-.sub.4]) = [f.sub.sulfur] [([r.sub.0]/r).sup.[beta]] [G.sub.1] molecules [(100 eV).sup.-1.], where [f.sub.Sulfur] is the sulfur weight fraction, r is the grain radius, [r.sub.0] = 50 [micro]m, [beta] [approximately equal to] 1.9, and [G.sub.1] = 0.4 [+ or -] 0.1. Equilibrium column densities N are derived for Europa's surface and follow the ordering N([[H.sub.2]S[O.sub.4]) [much greater than] N(S) > N(S[O.sub.2]) > N([H.sub.2]S). The lifetime of a sulfur atom on Europa's surface for radiolysis to [H.sub.2]S[O.sub.4] is [tau](-S)= 120[(r/[r.sub.0]).sup.[beta]] years. Rapid radiolytic processing hides the identity of the original source of the sulfurous material, but Iogenic plasma ion implantation and an acidic or salty ocean are candidate sources. Sulfate salts, if present, would be decomposed in Key Words: Europa; radiation chemistry; surfaces--satellite, magnetospheres.