We report the structural and optical properties of copper aluminium oxide (CuAlO2) thin films, which were prepared on c-plane sapphire substrates by the radio frequency magnetron sputtering method. Xray photoelectron spectroscopy (XPS) along with X-ray diffraction (XRD) analysis confirms that the films consist of delafossite CuAlO2 phase only. The optical absorption studies show the indirect and direct bandgap is 1.8 eV and 3.45 eV, respectively. Room temperature photoluminescence (PL) measurements show three emission peaks at 360 nm (3.45 eV), 470 nm (2.63 eV) and 590 nm (2.1 eV). The first one is near band edge emission while the other two are originated from defects. (C) 2011 Elsevier B. V. All rights reserved.