Cadmium indium oxide (CdIn 2 O 4 , CIO) thin films were prepared by r.f. reactive sputtering from a Cd-In alloy target under an Ar-O 2 atmosphere in order to fabricate gas-sensing devices where Corning CG-7059 glass was used as a substrate. An ultrathin, discontinuous layer of Pt was then sputtered onto the film surface, which improved the sensor's sensibility to the ethanol gas. The temperature dependence of sensitivity to ethanol gas for both pure and Pt-activated CIO films has been investigated.