Transparent conducting oxides thin films of copper aluminium oxide (CuA1O2) were prepared by spray pyrolysis technique on a glass substrate at temperature (500oC). The precursor solution was mixture of CuCl2 and anhydrous AlCl3 salts with different concentration (1:1), (1:2), and (2:1) of (Cu:Al) ratio. It appears that from XRD spectra the pure delaffosite phase of CuAlO2 was dominate at the ratio (1:1). UV-visible spectrum measurement showed highest absorption coefficient in the visible region at ratio (1:1). The optical alloweddirect and indirect band gap of thin films at ratio (1:1), (1:2) and (2:1) were estimated to be (2.9, 3, 2.6 and 1.2, 1.5, 1.4) eVrespectively. The extinction coefficient was also studied for different ratio. The effective ratio is (1:1) for photoelectric application.