We investigate the collisional damping of giant dipole resonance at finite temperature in the basis of a non-Markovian transport approach. We perform our calculations in Thomas-Fermi approximation by employing the microscopic in-medium cross-sections of Li and Machleidt and the phenomenological Gogny force. The results account for about 30% of the observed widths in Sn-120 and Pb-208 at finite temperatures
