The molecular geometry, vibrational frequencies, H-1 and C-13 NMR chemical shifts, UV-vis spectra, HOMO-LUMO analyses, molecular elektrostatic potantials (MEPs), thermodinamic properties and atomic charges of 3- and 4-Nitrobenzaldehyde oxime (C7H6N2O3) molecules have been investigated by using Hartree-Fock (HF) and density functional theory (DFT/B3LYP) methods with the 6-311++G(d, p) basis set. The calculated optimized geometric parameters (bond lenghts and bond angles), the vibrational frequencies calculated and C-13 and H-1 NMR chemical shifts values for the mentioned compounds are in a very good agreement with the experimental data. Futheremore, the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) have been simulated and the transition states, energy band gaps and molecular electrostatic potantial (MEP) maps for each oxime compound have been determined. Additionally, we also report the infrared intensities and Raman activities for the compounds under study. (C) 2011 Elsevier B.V. All rights reserved.