2-(3-Methyl-4,5-dihydro-1H-1,2,4-triazol-5-on-4-yl)-azomethine)-benzoic acid has been optimized using B3LYP/6-31G(d) and HF/6-31G(d) basis sets. Thus, the most stable geometrical comformer of compound was obtained. Proton Nuclear Magnetic Resonance (1H-NMR) and Carbon-13 Nuclear magnetic Resonance (13C-NMR) spectral values according to GIAO method was calculated using Gaussian G09W program package in gas phase and in DMSO solvent. Theoretical and experimental values were plotted according to δ exp=a+b.d calc. Theoretical spectral values of molecule were calculated and compared with experimental values. The veda4f program was used in defining Infrared (IR) data. The standard error values were found via the Sigma plot with regression coefficient of a and b constants. The vibrational frequency values of this molecule have been calculated by using 6-31G (d) basis set with DFT and HF methods. Then, these values are multiplied with appropriate adjustment factors. In addition, the, thermodynamics properties (heat capacity CV0, entropy S0 and enthalpy H0), electronic properties (electronegativity (χ), electron affinity (A), global hardness (η), softness (σ), ELUMO-EHOMO energy gap (ΔEg) and ionization potential (I), HOMO-LUMO energy), geometric properties (bond angles, bond lengths), dipole moments, mulliken atomic charges, total energy of the molecule were calculated with Gaussian 09W program on the computer.