This paper describes research performed in the Laboratory of Organic Chemistry, Showa Pharmaceutical University. Oxidation reactions involving the oxidase can be divided roughly into two kinds of reactions: The first involves electron removal from an aromatic ring or an active CH-bond. The other reaction involves hydrogen abstraction from an inactive CH-bond. The oxidase models, Fe(DMF)3Cl21+ and Fe(AN)63+/AN, which we have synthesized, have been shown to work by the former mechanism, and the models Fe(AN)63+-IO4-/AN, Fe(AN)62+-Ac2O-H2O2/AN, Fe(AN)62+-2PAH-5Py-Ac2O-H2O2/AN, Fe(PA)3(OH2)-H2O2/AN and Fe(PA)3(OH2)-O2-electrolysis/AN do so by the latter mechanism. Further, we found some iron(II or III)picolinate-H2O2/AN complexes have the 7α-hydroxylase-like activity.