New poly(aryl ether ketone) and poly(aryl ether sulfone) monodisperse model oligomers were synthesized in good yield via nucleophilic reactions. They were characterized by means of H-1 and C-13 NMR spectroscopy, and all chemical shifts were assigned to the corresponding nuclei. Both proton and carbon chemical shifts are very sensitive to the electronic environment generated by the O, CO and SO2 bridges, but in all oligomers, nuclei with similar electronic environments are very close to each other no matter what the sequence or the length of the oligomer is. Only quaternary carbons are more sensitive to the nature of the bridging groups, and therefore their chemical shifts can be of utility in sequencing the polymers.