Cobalt-nickel oxide films of known stoichiometry (x = Ni/(Co + Ni) = 0.30-0.63) were deposited on glass slides by using a spin-coating method and were UV irradiated for 2 h. The structure and morphology of thin films evidenced nanocrystalline spinel structures. Thin films with x = 0.63-0.5 have a mixed phase structure and good sensing properties for ethanol. Thin films with x = 0.30-0.40 have a single spinel phase, are ferrimagnetic and highly conductive at 300 K and have magnetoresistance ratios of 5-8%. Four-probe measurements indicate an insulator-metal transition at temperatures slightly below ferromagnetic Curie temperature. Metallic Ni and Co particles improve thin film functional properties. (C) 2011 Elsevier B.V. All rights reserved.