The time dependence of catastrophic optical mirror damage (COMD) is investigated for cw operation of AlGaAs‐GaAs quantum well lasers. The apparent Arrhenius parameters (i.e., the activation energy and pre‐exponential factor) for the rate process leading to COMD are determined. In particular, we compare the rate process for various cleaved facets with and without a subsequent plasma oxidation step. Analysis of the experimental Arrhenius parameters indicates that surface reactions on the corroded facets are responsible for facet degradation accompanied by heating. A tentative model of the facet heating that ultimately leads to COMD is presented.