The faster depleting natural reserves of fossil fuel and growing global climate change crisis have shifted the focus of researchers toward the extraction of bio-fuel and value-added chemicals from biomass. In this quest, supercritical (SC) water as a medium has been experimentally explored to derive bio-oil from biomass and deoxygenate the oxygenated compounds of it. Levulinic acid (LA) and pentanoic acid or valeric acid (VA) are two standard value-added products obtained from the biomass treatment. Thus, in this study, the authors report the kinetics of the conversion of levulinic acid to valeric acid at four different supercritical conditions using an implicit solvation model available within the framework of density functional theory (DFT) and compare them with their gas and aqueous phase counterparts. Prior to obtaining the new results, the present approach is first benchmarked with the existing experimental and theoretical literature under the supercritical water conditions. The conversion of levulinic acid is studied in two competing pathways. For each of the reaction pathways, the enthalpy and Gibbs free energy changes have been discussed. It is found that the production of valeric acid is equally likely to proceed by the protonation of the fourth carbon of the acid or by the protonation of the oxo-group at the fourth carbon atom. The solvent effects are found to be favorable, especially under two supercritical conditions, SC1 (rho = 0.089 g/cc, T = 773 K, P = 250 bar) and SC2 (rho = 0.109 g/cc, T = 723 K, P = 250 bar) compared to SC3 (rho = 0.190 g/cc, T = 700 K, P = 304 bar) and SC4 (rho = 0.360 g/cc, T = 723 K, P = 463 bar) conditions.