In this paper, we present the results of an investigation into the temperature dependence of fluctuation fields, activation volumes, and coercivity in Tb-Fe-Co magneto-optic thin films. Using the model of domain wall dynamics developed by Gaunt, both the temperature dependence of the intrinsic energy barrier distribution and the domain wall pinning regime are examined. The results show that at elevated temperatures, the intrinsic energy barrier distribution changes in a way that assists magnetization reversal, leading to greater activation volumes as the magneto-optic write temperature is approached. Analysis of coercivity as a function of temperature shows that these magneto-optic thin films are subject to a strong domain wall pinning regime. © 1997 IEEE.