The preferred reduced metal oxides for chlorine production are reduced oxide of ruthenium or iridium. The electrocatalyst may be a single, reduced platinum group metal oxide such as ruthenium oxide, iridium oxide, platinum oxide, etc. It has been found, however, that mixtures or alloys of reduced platinum group metal oxides are more stable. Thus, one electrode of reduced ruthenium oxides containing up to 25% of reduced oxides of iridium, and preferably 5 to 25% of iridium oxide by weight, has been found very stable. In a preferred composition, graphite may be added in an amount up to 50% by weight, preferably 10-30%. Graphite has excellent conductivity with a low halogen overvoltage and is substantially less expensive than plantinum group metals so that a substantially less expensive, yet highly effective electrode is possible.