Enzymatic activities of heme proteins, myoglobin (Mb) and hemoglobin (Hb), immobilized in the interlayers of magadiite nanoparticles under mild condition, toward the oxidation of o-phenylenediamine (OPD) in an organic solvent were firstly reported. The immobilized heme proteins showed higher stability than that of free Mb and Hb in organic toluene solution.