A combined theoretical and experimental investigation on a pharmaceutically important molecule 1,2,4-triazolo-[1,5-a]pyrimidine (TP) is presented in this study. Theoretical Density Functional Theory (DFT) study on the geometry, vibrational properties, energetics, and chemical shifts of the ground state of TP was carried out at B3LYP/6-311++G(d,p) level. Experimental infrared and Raman spectra of TP were presented and complete assignments of all vibrational modes were proposed by using the results of Total Energy Distribution (TED) analysis. The structure, spectra and energetics of TP in chloroform, carbon tetrachloride (CCl4), methanol, dimethyl, sulfoxide (DMSO) and water solvents have been calculated at the same level of theory by employing polarized continuum (PCM) model. Energies, relative stabilities, and dipole moments of TP were also evaluated in the gas phase and in polar and apolar solvents as well. (C) 2017 Elsevier B.V. All rights reserved.