The influences of various parameters in a single-step electrodeposition of CuInSe2 from aqueous solution containing CuCl2, InCl3, and SeO2, with sodium citrate as the complexing agent, are investigated. Co-deposition of CuInSe2 from a room temperature, aqueous bath of these electrolytes is accomplished by the aid of sodium citrate. In this work the optimum potential for deposition of CuInSe2 is found to be -0.5V vs. Ag/AgCl, the deposition time is 800 s, the concentration ratio of CuCl2, InCl3, and SeO2 is 9mM: 22mM: 22mM in aqueous solution, and the annealing temperature is 225 degrees C. Under the optimum conditions, crystalline layers of CuInSe2 having the chalcopyrite structure can be successfully synthesized. Cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray diffractometer (XRD), and energy dispersive X-ray spectrometer (EDX) were used to examine the electrochemistry, morphologies, structures, and compositions of CuInSe2 thin films deposited on ITO glass. (C) 2010 Elsevier B.V. All rights reserved.