A disinfectant combination comprises a first supply of a water-soluble hypochlorite; and a second supply of at least one saturated, water-soluble, physiologically acceptable carboxylic acid in solution in an alcoholic solvent which comprises ethanol and optionally water. The combination is used in a method of disinfection, in which a dosed amount of the first supply is mixed with a dosed amount of the second supply to form a disinfectant in situ, and the resulting combined solution, optionally diluted with further water, is applied to a surface or article to be disinfected. In a preferred embodiment, the combination is used for disinfection of endoscopes.