β-CuGaO2 shows promise as an absorber material for use in thin-film solar cells because of its direct and narrow band gap, causing intense light absorption and high theoretical maximum conversion efficiency. β-CuGaO2 thin films were fabricated using an ion-exchange whereby Na+ ions within a sputtered β-NaGaO2 thin film were replaced with Cu+ ions from a CuCl vapor. The band gap of the film was 1.45 eV, almost identical to that of the bulk material. The basic framework of the crystal structure and the orientation of the film were preserved following the ion-exchange. Methods of obtaining high-quality, stoichiometric β-CuGaO2 thin films free of cracks are discussed.