Abstract: The present invention relates to an oil-in-water emulsion which is suitable for processing photographic material. There is present or produced during the processing a substance which exerts its action on the photographic material from the aqueous phase. Contingent on the consumption the active substance is replenished or regenerated from the oily phase. The active substance is more readily soluble in the oily phase than in the aqueous one. The active substance may be, e.g., a dye bleach catalyst for silver dye bleach material or an alkylmercaptan, the latter acting as an antioxidant.