The DFT, QTAIM, NBO and ChelpG methods were used in a theoretical study of structural parameters, vibration stretch modes and absorption intensities, electronic properties, molecular orbital analyses and molecular topography of the heptamer C2H2···6(HF) complex. One of the great aims concerns to the studying of the proton donor structure, which is considered as two 3(HF) cyclic moieties. The structures of the HF trimer interact with acetylene in an opened configuration because the energies of the F···HF hydrogen bonds are enhanced from 34.45 to 58.43 as well as 61.48 kJ.mol-1. Moreover, instead of the unusual π····H hydrogen bonds formed on the middle of the π bond of acetylene, the more uncommon C···H contact was certified. The red-shifts on the stretch frequencies of HF bonds were evaluated aiming to unveil the covalent character in the F···HF hydrogen bonds.