Titanium dioxide codoped with carbon and nitrogen was synthesized by a microemulsion-hydrothermal process. There was a synergistic effect for the carbon and nitrogen-codoped TiO2, which offset the deficiencies of carbon or nitrogen single doped TiO2. The results showed that the photocatalytic activity of C and N-codoped TiO2 was considerably improved because the band gap of TiO2 was greatly narrowed by C and N-codoping.