We develop a reduced-complexity hybrid frequency/time-domain orthogonal frequency division multiplexing (OFDM) channel estimation algorithm for high-mobility scenarios where the channel varies significantly within each OFDM block, resulting in severe intercarrier interference (ICI). The algorithm exploits the banded and symmetric structure of the channel matrix in the frequencydomain and its sparse structure in the time-domain to achieve significant complexity reductions, which we quantify for the Digital Video Broadcasting-Handheld (DVB-H) system. Furthermore, we compare coherent and differential mobile OFDM detection for DVB-H.