Abstract: A process is proposed for the double-sided printing and/or coating of a substrate using at least one liquid or dry toner that has at least one polymer. It is provided that at least one toner layer or a first image that has at least one toner layer is transferred onto a first side of the substrate. Then, the toner is heated up to at least its glass transformation temperature, and fixed onto the substrate. In the process, the original glass transformation point of the toner shifts to a higher temperature level as a result of the cross-linking of its polymer chains, and the viscosity is increased. In a second processing step, at least one toner layer or a second image is transferred onto the second side of the substrate and heated up to a temperature that is equal to or greater than its glass transformation temperature.