Fourier transform infrared (FT-IR) spectroscopy in the region 400-4000 cm(-1), proton and carbon-13 NMR chemical shifts and UV-Vis. absorption wavelengths of 3-p-chlorobenzy1-4-(4-carboxybenzylidenamino)-4,5-dihydro-1H-1,2,4-triazol-5-one molecule have been experimentally investigated. For monomeric and dimeric forms of the title molecule, the optimized molecular structure analyses, vibrational wavenumbers, C-13 and H-1 NMR chemical shifts and electronic absorption wavelengths of the title molecule have been performed at DFT/B3LYP method with 6-311G(d,p) basis set. The HOMO and LUMO analyses have been theoretically done by using the mentioned calculation level. The obtained experimental values have been compared with calculated data. The computed vibrational frequencies, NMR chemical shifts and UV-Vis. wavelengths have been found to be in a good agreement with experimental values and spectral results of similar structures in the literature. (C) 2016 Elsevier B.V. All rights reserved.