Molecular dynamics simulations of aqueous solutions at infinite dilution of the reaction of water with formaldehyde, H2O + H2CO -> H2C(OH)(2), were performed using Lennard-Jones 12-6-1 potentials to describe the solute-solvent interactions, and TIP3P to describe the water-water interactions. The Morokuma decomposition scheme of ab initio interaction energies at the SCF level and the dispersion component at MP2 level were used to reproduce the molecular parameters of the solute-water interaction potential. The results show that the functions that use the EX-PL-DIS-ES interaction model to describe the solvation of the reactant and product systems lead to good values of the reaction (Delta G) and activation (Delta G(#)) free energy as compared with those from using AMBER-derived parameters, and with the available theoretical and experimental data.