Chalcopyrite CuInSe2(CIS) is considered to be an effective light-absorbing material for thin film photovoltaic solarcells. CIS thin films have been electrodeposited onto Mo coated and ITO glass substrates in potentiostatic mode at roomtemperature. The deposition mechanism of CIS thin films has been studied using the cyclic voltammetry (CV) technique. Acyclic voltammetric study was performed in unitary Cu, In, and Se systems, binary Cu-Se and In-Se systems, and a ternaryCu-In-Se system. The reduction peaks of the ITO substrate were examined in separate Cu2+, In3+, and Se4+ solutions.Electrodeposition experiments were conducted with varying deposition potentials and electrolyte bath conditions. Themorphological and compositional properties of the CIS thin films were examined by field emission scanning electronmicroscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The surface morphology of as-deposited CIS films exhibitsspherical and large-sized clusters. The deposition potential has a significant effect on the film morphology and/or grain size,such that the structure tended to grow according to the increase of the deposition potential. A CIS layer deposited at −0.6Vnearly approached the stoichiometric ratio of CuIn0.8Se1.8. The growth potential plays an important role in controlling thestoichiometry of CIS films.