Abstract: A transfer medium useful for preparing duplicates of originals such as printed matter. The transfer medium comprises a light-transmissive backing sheet, a layer coated on at least one major surface thereof containing a photooxidizable reactant and an oxygen-sensitizing dye in a film-forming binder and, over said layer, a top coat of an oxygen-permeable, low tack adhesive.Upon imagewise exposure to light, the transfer medium is desensitized in areas corresponding to the light image areas of the original, resulting in a latent image in the areas corresponding to the dark image areas of the original.The unoxidized photooxidizable reactant is capable of inter-reacting with a second reactant material borne on the surface of a receptor sheet at a conversion temperature between 70.degree. C. and 150.degree. C. to produce a visibly distinct reaction product.