A series of CuCeOx nanofiber catalysts with different Cu/(Cu + Ce) molar ratios were synthesized by an electrospinning method. The catalysts were evaluated for acetone oxidation at different temperatures (100-280 degrees C) with a GHSV of 79 000 ml g(-1) h(-1). The results showed that nanofiber catalysts possessed better catalytic performance than catalysts prepared by urea-nitrate combustion and sol-gel methods. An appropriate Cu/(Cu + Ce) molar ratio could greatly improve the activity of the nanofiber catalysts, and a significant improvement of the activity was obtained on the Cu0.50Ce0.50Ox nanofiber catalyst (similar to 100% acetone conversion at 270 degrees C). Characteristic analysis of prepared catalysts suggested (1) a special nanofibrous morphology with large specific surface area; (2) abundant oxygen vacancies and (3) cerium ions with unusual oxidation states were the main factors that would affect catalytic activity of CuCeOx nanofibers catalysts.