Electrochemical co-depositions of indium (In) with selenium (Se) and gallium (Ga) with selenium were carried out to obtain high-quality In-Se and Ga-Se films. The approach utilized full potential of complexation for the first time by using aqueous electroplating solutions containing complexing agents at alkaline regime. Complexing agents were employed to solubilize In and Ga ions at high pH and to bring their reduction potentials down, closer to that of Se. Since no appreciable complexation occurred between Se and the complexing agents, Se reduction potential could be independently controlled by the amount of dissolved Se. Tartrate and citrate were determined to be suitable complexing agents for In and Ga. By optimizing the concentrations of the metal salts, the complexing agents, the selenium source, pH and the electrodeposition current density, it was possible to obtain adherent and smooth In-Se and Ga-Se films with high repeatability and controllable In/Se and Ga/Se molar ratios.