In hydroxylation reactions: 2R3C–H + O2 \(\to\) 2R3C–OH and R3C–H + O2 + 2e– + 2H+ \( \to\) R3C–OH + H2O a substrate C–H bond is converted to an alcohol group. A mechanism of abstracting a hydrogen atom from the substrate by a high active intermediate, an iron(IV)-oxo porphyrin radical intermediate (Compound I) (rebound mechanism) was proposed for cytochrome P450. A similar rebound mechanism was suggested for the methane monooxygenase (MMO). The large number of complexes mimicking cytochromes P450 including iron protoporphyrin IX were synthesized and their hydroxylation activity was tested. To avoid problems associated with indirect pathway for conversion methane to methanol, which widely used in chemical industry using 1000 °C and elevated pressure, numerous complexes mimicking the structure and enzymatic activity of MMO were prepared. Among them are the following compounds: (μ-oxo)(μ-hydroxo)diiron (III) core [Fe2(O)(OH)(6TLA)2(ClO4)3], [Fe2(O)2(6TLA)2(ClO4)2] (II), a (-1,2-peroxo)bis(-carboxylato)diiron(III). According to the Shilov Cycle, CH4 oxidation in mild condition is catalyzed by PtCl2 in an aqueous solution, where PtCl6 2− acts as the ultimate oxidizing agent. Artificial hydrolases was utilized to catalyze the cleavage a number of substrates such as p-nitrophenyl acetate, glycerophospholipids, the phosphodiester bond of DNA, phosphate diester model of RNA, RNA model substrate 2-hydroxypropyl-4-nitrophenyl phosphate (HPNP). As a successful modeling nature’s catalytic triad, consisting of a hydroxyl group of a serine residue, an imidazole group of a histidine residue, and a carboxyl group of an aspartic acid, the miniature organic model of chymotrypsin, was designed on the basis of cyclodextrin. A water-soluble fullerene functionalized with carboxylic acid moieties, C60-1, mono- and binuclear metalloenzymes, carbon-based nanozymes, peptide-based compounds are examples of successful mimicry of hydrolases.