The electrochemical reduction of gold thiosulfate has been studied and compared to the reduction of gold cyanide. Gold thiosulfate is a potential replacement fur gold cyanide in electro and electroless plating baths. Gold thiosulfate has a more positive reduction potential than gold cyanide and eliminates the use of cyanide. The standard heterogeneous rate constant, transfer coefficient, and diffusion coefficient for gold thiosulfate reduction were found to be 1.58 x 10(-3) cm/s,0.23 and 7 x 10(-6) cm(2)/s, respectively. The effect of sulfite as an additive to gold thiosulfate solutions was examined.