CuInSe2/CdS thin-film heterojunction solar cells were fabricated entirely by chemical bath deposition technique. The illuminated J-V characteristcs of the devices prepared with different thicknesses of CdS and CuInSe2 were studied. The typical solar cell parameters obtained for the best cell are: V-oc = 365 mV, J(sc) = 12 mA/cm(2), FF = 61%, and eta = 3.1% under an illumination of 85 mW/cm(2) on a cell of active area 0.1 cm(2). The J-V and C-V characteristics under dark condition and the spectral response were also studied for the best cell. The diode quality factor obtained is 1.7.