In this study, the synthesis, spectroscopic (FT-IR, micro-Raman and UV-Vis) investigations and antioxidant activity of 1-acetyl-3-methyl-4-[3-methoxy-4-(4-methylbenzoxy)benzylidenamino]-4,5-dihydro-1H-1,2,4-triazol-5-one molecule have been verified. The quantum chemical computations (molecular structure, vibrational frequencies, electronic absorption maximum wavelengths in gas phase and ethanol solvent, HOMO-LUMO, molecular electrostatic potential (MEP) and natural bond orbital (NBO) analyses, nonlinear optical (NLO) and thermodynamic properties and atomic charges of the title compound have been performed using the DFT/B3LYP method with 6-31G(d) basis set. The energetic behavior of title molecule in different solvent media was investigated at the B3LYP/6-31G(d) level by using the integral equation formalism polarizable continuum model (IEFPCM). A comparison between the calculated results and experimental data exhibits a very good agreement. (C) 2013 Elsevier B.V. All rights reserved.