Abstract: Activated cathode for use in aqueous solution electrolysis comprises (a) a base plate made of a metal selected from the group consisting of titanium, tantalum, zirconium, niobium or an alloy essentially consisting of combination of those metals and (b) a metal oxide layer formed on the surface of the base plate, said metal oxide essentially consisting of an oxide of one or more metal elements selected from the group consisting of ruthenium, rhodium, palladium, osmium, iridium and platinum in the groups VIII--5 and VIII--6 of the periodic table and if necessary, (c) an oxide of one or more metal elements selected from the group consisting of calcium, magnesium, strontium, barium and zinc in the group II and chromium, molybdenum, tungsten, selenium and tellurium in the group VI.