Simulation of the enzymatic function of cytochrome P-450 with transition metal complex catalysts has resulted in finding biomimetic and catalytic oxidations of amines, amides, beta-lactams, alcohols, phenols and hydrocarbons by using ruthenium catalyst and peroxide. Further study revealed that the catalytic formation of peracids in situ from aldehydes and molecular oxygen enables the aerobic oxidation of beta-lactams, alcohols, alkanes and ketones in the presence of metal catalyst under mild conditions.