Copper bismuth selenide thin films have been prepared by potentiostatical electrodeposition from an aqueous solution containing CuCl2, Bi(NO3)3 and H2SeO3 followed by post annealing treatment. Cyclic voltammetry (CV) test was used to investigate the electrodeposition mechanism. The suitable deposition potential for film preparation was determined combining with CV, composition and morphology studies. The as-deposited films are amorphous in nature and the amorphous-to-crystalline transition can be obtained by annealing treatment at 450°C. The morphological, compositional, structural, optical and electrical properties of the prepared films were studied via environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, optical absorption and photoelectrochemical tests, respectively. The annealed film with triclinic structure exhibits high absorption coefficient of 0.5–1.2×105 cm−1, an optical band gap of 1.50eV, a p-type conductivity and good photoactivity, indicating potential application in photoelectric conversion.