[en] Reactions of the monovalent metal ions Cd⁺, Co⁺, Ni⁺ and Zn⁺ with electron acceptors in neutral aqueous solution have been studied and three types identified: (a) addition, M⁺ + 0₂ → M0₂⁺ (M = Ni), and M⁺ + olefin → (M - olefin)⁺; (b) oxygen atom transfer, M⁺ + N₂0 → M0⁺ + N₂; (c) electron transfer, M⁺ + S₂0₈^2- → M²⁺ + S0₄^- + S0₄^2-. In reaction (b) when M = Co, long lived Cosup(III) species are produced. Evidence is also presented for the oxidation of Co²⁺ by 0H (k = 8 x 10⁵ dm³ mol^-1 s^-1) and by S0₄^-(k approximately 2 x 10⁶ dm³ mol^-1 s^-1) in neutral solution. (author)