This invention relates to solutions of dithionic acid and/or dithionate salts which use in metal finishing processes such those used for the cleaning, activating, electroplating, electroless plating, conversion coating and/or other pre-treatment or post-treatment of a metallic surface. In particular the solutions are a useful electrolyte for the electroplating of metallic coatings, especially, Sn, Cu, Ni, Zn and precious metals, onto metal or plastic substrates and/or other surfaces.