The aim of the present theoretical study is to examine the dioxygen activation process occurring at the metalloporphyrin complexes as the first step of the selective oxidation of hydrocarbons, with the stress put on how this may be affected by the type of the central metal. In order to do so, the properties of the porphyrin complexes of Mn, Mo, and Co are discussed by means of quantum chemical calculations within Density Functional Theory (DFT). As a first step, the dioxygen binding by the above-mentioned systems is considered, followed by the study of the interactions of one and two hydrogen atoms with different types of the adsorbed O2 molecule onto the porphyrin complex. Finally, the stability of the formed oxo species is discussed.