CuGaSe���/CuInSe��� tandem junction solar cell is currently being pursued to be a low cost and high efficiency renewable energy source. A reported theoretical efficiency of 33.9% solar cells has been the motivation to fabricate CuGaSe��� films in a simple and low cost method. Electrodeposition is a potentially suitable method to obtain the CuGaSe��� films. A better understanding of the electrodeposition process is required to optimize the process. Focusing on the manufacture of CuGaSe��� film, the reaction accompanying the electrodeposition of CuGaSe��� using rotating disk electrode from cupric sulfate, selenious acid and gallium chloride solution in sulphate medium were studied by voltammetry. Cyclic and rotating disk voltammetry in pure and binary systems were performed in order to understand the complexity of Cu + Ga + Se systems. Diffusion coefficients of Cu(II) and Se(IV) were determined using Levich equation to be 6.93x 10������ cm��/s and 9.69x 10������ cm��/s, respectively. The correlations between supporting electrolytes, flux ratios, working electrodes and films were investigated experimentally. The deposited films were characterized by Induced Couple Plasma Spectrometry, X-Ray Diffraction, Scanning Electron Microscopy and Energy Dispersive X-Ray. CuGaSe��� is formed via the reaction of CuSe compound reduction and Ga(III) and higher gallium concentration will favor the formation of CGS film. The incorporation of gallium is highly depending on the pH (higher is better). An impinging flow electrochemical reactor was built as an alternative approach for electrochemical deposition method. Preliminary experiments of copper and copper selenide electrodeposition were conducted, and the results were comparable to the rotated disk voltammetry. / Graduation date: 2004