Abstract <p>Acetic acid is a fundamental organic molecule with widespread applications in industrial processes, biological systems, and catalysis. One key attribute of acetic acid is that it can form stable hydrogen-bonded networks in both the gas phase and the solution phase, particularly the cyclic dimer. Acetic acid molecules may form hydrogen bonds either with their kind or adjacent solvent molecules, depending upon the polarity of the solvents. The mechanism of cyclic dimer formation and the energetics associated with the concerted DPT (double proton transfer) in the cyclic dimer were investigated computationally by means of DFT (Density Functional Theory) and the NEB-TS (Nudged Elastic Band with TS optimization) methods. Additionally, structures of two hydrate complexes of acetic acid and two water-separated acetic acid dimers were isolated from the MD (molecular dynamics) simulation performed on an aqueous solution of acetic acid and the energy barriers associated with the concerted proton transfers were studied using the DFT and NEB-TS methods. The results provide insights into the potential energy surfaces associated with the concerted proton transfers in the hydrate complexes of acetic acid and the water-separated acetic acid dimers, shedding light on the increased kinetic hindrance along the concerned path.</p> Graphical abstract <p></p>