Abstract: The object of this invention was to find a Sn.sup.II -containing electrolyte for galvanizing or coloring anodized aluminum and its alloys which, in the first place, contains substances which stabilize Sn.sup.II better than substances used up to now for this purpose, secondly, exhibits better throwing power and therefore better current distribution and thirdly is not harmful to the environment, or at least not to such a degree as the electrolytes used up to now. The electrolyte of the invention is such that it contains one or more additives having the general structure R.sub.1 --S--R.sub.2, where R.sub.1 can be a hydrogen atom or a hydrocarbon group with or without a hydroxy or carboxy group, R.sub.2 a hydrocarbon with hydroxy or carboxy group. A particularly preferred additive is 2.2'-di-hydroxy-di-ethyl-thio-ether (or 2.2'-thio-di-ethanol) HOCH.sub.2 CH.sub.2 --S--CH.sub.2 CH.sub.2 OH.