Ternary CuIn5S8 spinel thin films were deposited on indium tin oxide (ITO)-coated glass substrates using a one-step electrodeposition method. A new procedure for the deposition of CuIn5S8 samples is reported. Prior to the deposition, a cyclic voltammetric study was performed in unitary (Cu, S, In) systems, binaries (Cu-S, In-S) systems, and ternary Cu-In-S system. The influence of various deposition potentials on structural, morphological, optical and electrical properties of samples was investigated. Based on these studies, X-ray diffraction patterns show that CuIn5S8 cubic spinel phase was the main constituent of the deposited layers at applied potential of -1 V (vs. Ag/AgCl). From (AFM) analysis, it was found that the surface morphology, grain size roughness and thickness were strongly affected by varying the deposition potentials. At -1 V (vs. Ag/AgCl) an optical band-gap of approximately 1.54 eV for this material was determined by optical transmission spectroscopy. At potentials more negative than -0.8 V (vs. Ag/AgCl) the film is converted to n-type and exhibits lower resistivity. (C) 2013 The Electrochemical Society. All rights reserved.