Abstract: A process is described for the dyeing and printing of paper materials by the use of developing dyestuffs, in which process diazo components and heterocyclic coupling components containing a 6-membered heterocyclic radical having one ring nitrogen atom are applied in any sequence, either successively or simultaneously onto or into the paper material to be dyed or printed, and coupled together in alkaline, neutral or acid medium, whereby it is possible using only a single coupling component to obtain on the material, merely by variation of the diazo component, a shade of color ranging from yellow to black.