Abstract: Storage stable, aqueous acidic solutions having a pH in the range of from 1 to 5 comprising at least one ester peracid having general formula where R represents an alkyl group having from 1 to 4 carbons and x equals 1 to 4, are provided. The solutions can be prepared by contacting an aqueous solution of a carboxylic compound having general formula where x is from 1 to 4 and R represents an alkyl group having from 1 to 4 carbons with an inorganic peroxygen compound, preferably hydrogen peroxide, at a pH of less than 4 until at least some ester peracid is produced, and thereafter adjusting the pH to be in the range of from 1 to 5, if necessary.