Herein, we report the EPR spectroscopic study of the bioinspired catalyst systems for selective hydrocarbon oxofunctionalizations based on dinuclear ferric complexes with TPA* and PDP* aminopyridine ligands, hydrogen peroxide, and acetic acid (TPA* = tris(3,5-dimethyl-4-methoxypyridyl-2-methyl)amine, PDP* = bis(3,5-dimethyl-4-methoxypyridyl-2-methyl)-(S,S)-2,2′-bipyrrolidine). Using very low temperatures, −75 to −85 °C, the extremely unstable and reactive iron–oxygen intermediates, directly reacting with olefins even at −85 °C, have been detected for the first time. Their EPR parameters (g₁ = 2.070–2.071, g₂ = 2.005–2.008, g₃ = 1.956–1.960) were very similar to those of the known oxoiron(V) complex [(TMC)Fe^V═O(NC(O)CH₃)]⁺ (g₁ = 2.053, g₂ = 2.010, g₃ = 1.971, TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane). On the basis of EPR and reactivity data, the detected intermediates were assigned to the Fe^V═O active oxidizing species of the catalyst systems studied.