Abstract: Single bath electrodeposition of polycrystalline Cu(In,Ga)Se2 thin films for photovoltaic applications is disclosed. Specifically, Cu(In,Ga)Se2 was deposited onto Mo electrodes from low concentration buffered (pH 2.5) aqueous baths containing CuCl2, InCl3, GaCl3 and H2SeO3. Moreover, buffered aqueous baths are disclosed wherein Se4+/Cu2+ concentration ratios were controlled to optimize Se and Cu levels, while In3+ concentration was adjusted to control deposited In and Ga. Further disclosed are pre- and post-deposition processing methods resulting in smooth, compact, crack-free films of near stoichiometric values. Post deposition heat treatments on electrodeposited CuInSe2-based films in selenium and sulfur containing atmosphere are described. CuInSe2-based films from a single bath deposited onto Mo electrodes from low concentration aqueous baths.