Nanometer powders of the CdO-In2O3 system were prepared by a chemical coprecipitation method. The effects of preparation conditions on the phase constituents of the powders were investigated. Pure fee spinel CdIn2O4 phase with a nonstoichiometric formula of Cd(In1-xCdx)(2)O4-x was obtained at a temperature above 500 degrees C for a mixed precursor with Cd/In = 1.3/2. Atomic absorption spectrum analysis revealed that the molar ratios Cd/In of the precipitate and the precipitate sintered at 600 degrees C for 4 h were both 1.08/2. The crystallite size of the powders was in the range of 14-26 nm, increasing with firing temperature. The phase was stable up to at least 800 degrees C. The conductance-temperature characteristics of the nano-CdIn2O4 spinel phase were studied and determined by oxygen adsorption on the surface of the materials. The investigation of gas-sensing performance of the sensors demonstrated that the nano-CdIn2O4-based sensors have fairly high sensitivity and selectivity to C2H5OH and are promising for practical development.