Pure hydroxides of cobalt, nickel and cadmium have been synthesized by a new route. The powdered metals have been oxidized by dioxygen in aqueous ammonia. The reactions have been carried out at ambiant temperature and pressure. Cobalt hydroxyde Co(OH)2 is slowly oxidized to CoOOH by subsequent exposure to dioxygen the Ni(OH)2 synthesis is easier if nickel metal is activated by exposure to dihydrogen at about 300-degrees-C.