In this study, the compound 2-(ethylthio)pyrimidine-4,6-diamine (ETPD) was re-synthesized and its single crystals were obtained by slow evaporation of ethanol solution. The characterization of the molecule was done experimentally and theoretically. The single-crystal X-ray diffraction analysis shows that ETPD crystallizes in the orthorhombic space group P2(1)2(1)2(1). The ground state geometry, vibrational spectra, NMR spectra, frontier molecular orbitals and also the map of molecular electrostatic potential (MEP) of ETPD obtained using DFT calculations were evaluated in detail. In addition, the global reactivity descriptors were obtained within the frontier molecular orbitals calculations. The comparison of the DFT results obtained by different methods and basis sets with X-ray diffraction analysis display the DFT can well reproduce the structure of the compound. (C) 2017 Elsevier B.V. All rights reserved.