Bright Co-W alloy on steel is obtained from the optimised bath with the operating conditions of cobalt sulphate 0.15.M sodium tungstate 24 gpl, ammonium chloride 0.2 M, sodium citrate 0.2 M, dimethyl sulphoxide 0.06 M, pH 8 at 4 Adm(-2). The hardness of the alloy deposit is two times that of cobalt deposit. The corrosion resistance in 1.0 M acidic solutions for Co-20% W alloy is in the order of HCl > H2SO4 > HClO4. The deposition of cobalt oil platinum takes place from cobalt citrate complex, This citrate complex undergoes successive electron transfer, During the Co-W alloy deposition on platinum, cobalt tungstate complex undergoes reduction to form an alloy. The dissolution of Co-W alloy film occurs from Co-W intermediate phase.