This letter compared catalase-, peroxidase- and cytochrome P450-like catalytic activities of 15 water-soluble metalloporphyrins produced from Fe, Mn and Co ions and 5 porphyrins. The metalloporphyrins with Fe and Mn as central ions show relatively high catalytic activities of catalase and peroxidase at pH 11.0. Only Mn-meso-tetrakis (4-N-methylpyridinium) porpho-phine of the 15 metalloporphyrins exhibits high cytochrome P450-like activity. Effects of imidazole on the catalytic reactions were also studied. This letter compared catalase-, peroxidase- and cytochrome P450-like catalytic activities of 15 water-soluble metalloporphyrins produced from Fe, Mn and Co ions and 5 porphyrins. The metalloporphyrins with Fe and Mn as central ions show relatively high catalytic activities of catalase and peroxidase at pH 11.0. Only Mn-meso-tetrakis (4-N-methylpyridinium) porpho-phine of the 15 metalloporphyrins exhibits high cytochrome P450-like activity. Effects of imidazole on the catalytic reactions were also studied.