Hydrogenases are promising candidates for the catalytic production of green energy by means of biological ways. The major impediment to such a production is rooted in their inhibition under aerobic conditions. In this work, we model dioxygen migration rates in mutants of a hydrogenase of Desulfovibrio fructusovorans. The approach relies on the calculation of the whole potential of mean force for 02 migration within the wild-type as well as in V74M, V74F, and V74Q mutant channels. The three free-energy barriers along the entire migration pathway are converted into chemical rates through modeling based on Transition State Theory. The use of such a model recovers the trend of O-2 migration rates among the series.