Effect of composition and morphology on the catalytic activity in CO oxidation of Co-, Cu-, Ce-containing oxide materials prepared by citrate method has been studied. It was shown that composites consist of well-dispersed oxides Co3O4, CuO and CeO(2)with average crystallite sizes 13-24 nm, 14-26 nm and 3-7 nm, respectively. It was established that Co-, Cu-, Ce-oxide nanocomposites demonstrated higher catalytic activity in CO oxidation in comparison with individual oxides. The ternary oxide system Co3O4-CuO-CeO2(Co:Cu:Ce=10:1:1) was found to possess the highest catalytic activity due to formation finely dispersed particles of CuO and CeO(2)oxides simultaneously with nanosized Co(3)O(4)species and formation of large quantity of mobile oxygen at the interfaces between the oxide nanoparticles.