Abstract: A method and a composition for disinfecting matter or materials such as medical instruments, operating rooms, examining tables, walls, windows, floors, solutions, porous substances and the like contaminated with bacteria, bacterial spores, fungi, or viruses is disclosed. The composition consists of a mixture of a peroxymonosulfate and a carbonyl-containing compound and reaction products thereof and is preferably dioxirane formed by in situ oxidation of a ketone or aldehyde by the peroxymonosulfate in aqueous solution. Carbonyl-containing compounds that have been tested include acetone, 2-pentanone, 4-hydroxy-4-methyl-2-pentanone, and camphorsulfonic acid. The method includes providing a solution containing the dioxirane reaction mixture and contacting the matter or materials with it at room temperature for a time sufficient to disinfect and sterilize the matter or materials.