Hydrogen bonding properties of H2SO4/HNO3/H2O ternary molecular clusters have been studied by means of structural, energetic, topological, and spectroscopic perspectives. The roles of the hydrogen bonds in the formation of these clusters are considered according to the molecule positions (proton donor or proton acceptor) in the clusters. 33 stable conformers were identified on the potential energy surface. The global minimum one was obtained when HNO3 donates a proton to H2SO4, however, the cooperativity effect contribution was found to be significant for the cluster where HNO3 acts as a proton donor to an H2O molecule. (C) 2017 Elsevier Inc. All rights reserved.