Isomers of trans-1,4-Dinitroglycoluril (trans-DINGU) and their 1,3-tautomers are considered within the constraints of B3LYP/6-31++ G (d, p) and B3LYP/CC-PVTZ levels of DFT calculations. Additionally, the interactions of these isomers and proton in vacuum are investigated. The data have revealed that two of the three isomers undergo C-H bond cleavage as the result of interaction with proton in vacuum. The total energies, some structural properties, the calculated IR and UV spectra are discussed. (C) 2017 The Author. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).