Two new symmetrical and unsymmetrical diiron(III) complexes were synthesized and characterized by X-ray diffraction analysis, mass spectrometry, UV-visible and Mössbauer spectroscopies. They proved to be good catalysts for alkene and alkane oxidation reactions by H₂O₂ in acetonitrile solution, and interesting effects of both the nature and the symmetry of the complexes were observed on catalysis in the presence of water.