A thermal dye transfer assemblage comprising:(a) a dye-donor element comprising a support having thereon a dye layer comprising a dye dispersed in a polymeric binder, the dye being a cationic dye or a deprotonated cationic dye which is capable of being reprotonated to a cationic dye having a N--H group which is part of a conjugated system, and(b) a dye-receiving element comprising a support having thereon a polymeric dye image-receiving layer, the dye-receiving element being in a superposed relationship with the dye-donor element so that the dye layer is in contact with the dye image-receiving layer, the dye image-receiving layer comprising a polyester ionomer comprising a polyester backbone containing units of a sulfonic acid or a sulfonimide or their salts, with the proviso that when the dye is a deprotonated cationic dye which is capable of being reprotonated to a cationic dye having a N--H group which is part of a conjugated system, the dye image-receiving layer comprises a polyester ionomer comprising a polyester backbone containing units of a sulfonic acid or a sulfonimide.