Non-equilibrium dynamics of photoexcited carrier in cadmium oxide thin films were examined by the pump-probe transient optical transmission measurement technique using the second harmonics (400 nm) of femtosecond pulses as a pump light. Time-dependent blueshift of the absorption edge was clearly observed and it reached a maximum at similar to1 ps after the pumping. The magnitude of the blueshift increases with pump light power, which was well fitted to Burstein-Moss formula. The relaxation time of excited electrons from the bottom of the conduction band was obtained similar to350 ps and an effective mass for the electron carrier was estimated as similar to0.3m(e). (C) 2003 Elsevier B.V. All rights reserved.