CuGaxIn1-xSe2 is a potential absorber material for the fabrication of heterojunction solar cells. CuGaxIn1-xSe2 films (0.5-3.0 mu m), grown at T-s=598-648 K on Corning 7059 glass substrates using the flash evaporation technique, were p-type, nearly stoichiometric and polycrystalline with a chalcopyrite structure. Polycrystalline thin film n-CdS/p-CuGaxIn1-xSe2 heterojunctions were fabricated with a back-wall configuration and the junction characteristics were evaluated in terms of current density-voltage, capacitance-voltage and spectral response measurements. The electrical conversion efficiency obtained for cells with an active area of 1 cm(2) under a solar input of 85 mW cm(-2) was 7.6%, 6.7% and 6.5% respectively for CuGaxIn1-xSe2 cells with x = 0.25, 0.50 and 0.75.