[en] Two oligopeptides (N-Ac-Gly-Met-Gly and N-Ac-Gly-Gly-Gly-Met-Gly-Gly-Gly) containing internal methionine residues have been studied. The ·OH-induced reaction pathways in N-Ac-Gly-Met-Gly have been characterized by the complementary pulse radiolysis measurements coupled to time-resolved UV-VIS spectroscopy. Differences between two peptides in the transient yields are: a preference for the intramolecular sulfur-nitrogen bonded radical cations over the intermolecularly sulfur-sulfur three-electron bonded dimeric radical cations and substantially higher yields of C_α-centered radicals and glycyl radicals, as the size of the model peptide increases