AbstractThe1H and13C NMR spectral data of benzimidazole, benzoxazole, benzothiazole andN‐methylbenzimida‐zole and of their 2‐N,N‐dimethylamino derivatives are reported. The spectra were recorded in acetone‐water solution. The chemical shifts of these molecules are compared with those of the corresponding cations obtained byN‐protonation andN‐methylation of the neutral molecules. The carbon atoms C‐4, C‐5, C‐6 and C‐4a show a qualitatively identical behaviour, moving to higher field when the cations are formed from the benzazoles examined, but a different behaviour is found for C‐2, C‐7 and C‐7a, which depends on the heterocyclic ring, on the presence of the substituent in position 2 and on the type of cation formed (N‐protonation andN‐methylation cause different effects). The conversion of benzazoles into the corresponding cations causes all1H chemica