OFDM is a powerful transmission technique to achieve high data rates and to suppress intersymbol interference (ISI) in frequency-selective fading channel. However in wireless environment, especially in the case of high speed train, the channel is time variant because of the relative motion between the transmitter and receiver. The fast channel variations can he modeled by Doppler spread change over one symbol OFDM duration. In such propagation conditions, the orthogonality among subcarriers is destroyed, which result in intercarrier interference (ICI) that may degrades severely the bit error rate performance of OFDM systems. In this paper, we address adaptive channel equalization in OFDM systems Kalman filter for channel tracking and decision feedback equalizer (DFE) is proposed to reduce the performance degradation due to ICI. Simulation and performances of the proposed equalized OFDM system are earned out for different mobile speed