Fe(III)T4MPyP in water T=30°C; the catalyst Fe(III)T4MPyP is 5,10,15,20-tetra(N-methyl-4-pyridyl)-porphyrinatoiron(III) pentachloride; pH 9.2; investigation of the dependence of velocity constant on ionic strength, pH and t-butyl hydroperoxide concentration; Rate constantKineticsMechanism;