Abstract: A method of cleaning photographic apparatus comprises contacting the apparatus with an aqueous composition containing a peroxo compound chosen from one or more of:(a) an ionic peroxide of the formula M.sub.x O.sub.2, where M is a single charged cation and x is 2, or M is a double charged cation and x is 1, or(b) a peroxo acid of sulfur, phosphorous, carbon or boron, or a salt thereof, or(c) hydrogen peroxide, or a substance that contain hydrogen peroxide.Preferably the composition also contains acid, and/or at least one catalyst or accelerator compound. The peroxo compound may be one or more of: an ionic peroxide chosen from an alkali metal, alkaline earth metal, or ammonium, peroxide, or a peroxo acid chosen from peroxodisulfuric acid, peroxomonosulfuric acid, peroxodicarbonic acid, peroxodiphosphonic acid, per-organic acids, or a salt thereof. A preferred peroxo compound is a persulfate salt. The invention also concerns a formulation for cleaning photographic equipment.