CuIn1-xGaxSe2 (CIGS) thin films were formed from an electrodeposited CuInSe2 (CIS) precursor by thermal processing in vacuum in which the film stoichiometry was adjusted by adding In, Ga and Se. The structure, composition, morphology and opto-electronic properties of the as-deposited and selenized CIS precursors were characterized by various techniques. A 9.8% CIGS based thin film solar cell was developed using the electrodeposited and processed him. The cell structure consisted of Mo/CIGS/CdS/ZnO/MgF2. The cell parameters such as J(sc), V-oc, FF and eta were determined from I-V characterization of the cell.