Electrochemically activated catholyte – fresh or low-mineralized water, in which due to unipolar electrochemical exposure (near the cathode of electrochemical system) there have been formed and are present meta-stable products of cathode electrochemical reactions, in particular, molecular ions НО2– , О2– , ОН–. Electrochemically activated catholyte features electron-donor ability, that is, it is a strong reductant and /or reduction catalyst in various physico-chemical reactions including biochemical ones.