Solutions 0.2 mol dm⁻³ in Ga^I, prepared by dissolving Ga₂Cl₄ in dry acetonitrile, are stable for more than seven days and may be diluted 300- to 1000-fold with O₂-free water to give Ga^I preparations that may be handled by conventional techniques; these Ga^I(aq) solutions readily reduce I₃⁻, Br₂(aq), IrCl₆²⁻, Fe(bipy)₃³⁺ and aquacob(III)alamin (B_12a) but are inert to Co(NH₃)₅Cl²⁺ and Co(NH₃)₅Br²⁺; reduction of HCrO₄⁻ in 2-ethyl-2-hydroxybutanoate buffers yields the Cr^IV chelate of the buffering anion.