CdIn2O4 sensor with high sensitivity and excellent selectivity for H2S gas was synthesized by using sol-gel technique. Structural, electrical and gas sensing properties of doped and undoped CdIn2O4 thick films were studied. XRD revealed the single-phase polycrystalline nature of the synthesized CdIn2O4 nanomaterials. Since the resistance change of a sensing material is the measure of its response, selectivity and sensitivity was found to be enhanced by doping different concentrations of cobalt in CdIn2O4 thick films. The sensor exhibits high response and selectivity toward H2S for 10 wt.% Co doped CdIn2O4 thick films. The current-voltage characteristics of 10 wt.% Co doped CdIn2O4 calcined at 650 degrees C shows one order increase in current with change in the bias voltage at an operating temperature of 200 degrees C for 1000 ppm H2S gas. (C) 2011 Published by Elsevier B.V.