The H-1 and C-13 NMR chemical shifts of the 2,4-difluorobenzaldehyde isonicotinoylhydrazone (I) and 2,3-dichlorobenzaidehyde isonicotinoylhydrazone (II) were determined with the help of full spectral analysis. The geometry and electronic structure of the title compounds were investigated at both the ab initio Hartree-Fock and the B3LYP levels with 6-31+G(d,p) basis set. The NMR data were calculated by means of the CIAO, CSGT, and IGAIM methods. All quantum-chemical calculations, including those of NMR data, were performed by ab initio level HF and DFT methods. Excellent agreement between the theoretical and experimental results was found for the HF level H-1 and C-13 chemical shifts. The parameters of molecular geometry and H-1 and C-13 chemical shift values of the title compounds (I, II) in the ground state have been calculated and and compared with corresponding experimental result. (C) 2009 Wiley Periodicals, Inc, Concepts Magn Reson Part A 34A: 297-304, 2009.