Aziridines are important building blocks for the synthesis of a wide range of organic compounds, including biologically active compounds and pharmaceuticals. The development of more cost-effective catalysts for atom transfer reactions is a continuing area of research in chemistry. Transition metal complexes have been shown to catalyze the aziridination of olefins, however, most require expensive metal ions or complex ligands. Meso-tetra(N-methyl-4-pyridyl)porphyrin (TMPyP4) is a highly charged, planar ligand that has been used to support manganese(III) in complexes like Mn[TMPyP4]I5. Herein we report the optimization of the reaction conditions for the aziridination of olefins in water and buffered solutions catalyzed by Mn[TMPyP4]I5. The reaction conditions optimized include pH range, temperature, and reaction time. Additionally, nitrogen sources, nitrogen source/olefin ratios, and catalyst loading were optimized. In buffered solutions, Mn[TMPyP4]I5 can effectively catalyze the generation of aziridines from various aromatic and aliphatic olefins with Chloramine T in moderate to good yields (43-93 %).