A method of sterilizing a material, said method comprising the steps of: a) providing a sterilizing composition comprising (i) peracetic acid and (ii) a stabilizer selected from the group consisting of citric acid, isocitric acid, aconitic acid and propane-1,2,3-tricarboxylic acid; b) introducing such sterilizing composition into a hot gaseous stream to produce a peracetic acid vapor; and c) contacting such peracetic acid vapor with the material to be sterilized. The use of such an organic acid stabilizer results in an unexpected reduction in the amount of residue deposited on the heating surface employed to vaporize the sterilizing composition.