a thermal dye transfer assemblage comprising : a dye - donor element comprising a support having thereon sequentially repeating dye layer patches of a dye dispersed in a polymeric binder , at least one of the dye patches containing a pendant basic - substituted dye having the formula : a -. sub . m wherein : a represents a thermally transferable dye residue , l represents a divalent linking group , b represents a basic substituent , and m represents an integer of from 1 to 3 ; and 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 polymeric dye image - receiving layer , the polymeric dye image - receiving layer containing a hydrated transition metal or metalloid salt of a strong acid .