Disinfectant compositions disclosed herein comprise at least one biocidal quaternary ammonium compound, hydrogen peroxide, and optionally inorganic acid and/or organic acid. Particularly, a composition comprising a biocidal quaternary ammonium chloride compound, hydrogen peroxide, and C1 to C8 carboxylic acid, mono-, di- and tricarboxylic acid enhances significantly its antimicrobial activities of either hydrogen peroxide or the quaternary ammonium chloride alone.
