A CuIn(SxSe1-x)(2) alloy thin-film was prepared by selenization of CuInS2: its composition ratio x can be controlled by the number of selenization cycles implemented. Crystallinity of the films was improved by annealing in vacuum. The resistivity of the film was about 1 Omega cm and increased by one to two orders of magnitude after KCN treatment. An 8.1% efficiency solar cell was obtained by using this annealed alloy thin-film.