Alkane hydroxylation by peroxy acids proceeds by a synchronous nonconcerted peroxy oxygen insertion into the C-H bond according to density functional theory. A comparable reaction sequence, initiated by homolytic peroxy bond cleavage, can be formulated for the alkane hydroxylation by the cytochrome P450 hydroperoxoheme Compound 0. This hydroxylation reaction proceeds by a two-step process because the formed reactive intermediate, Compound II, is significantly stabilized.