The ring-opening and decarboxylation reaction of γ-valerolactone (GVL), yielding a mixture of butene isomers, constitutes an important transformative step for the upgradation of biomass-derived precursors into high value fuels and chemicals. In this study, density functional theory (DFT) simulations were utilized to gain insights into the ring-opening of GVL in presence of Brønsted acid promoted γ-Al2O3 catalyst. DFT simulations suggested towards the formation of stable oxocarbenium ion of GVL on the γ- Al2O3 surface via a proton transfer to the carbonyl oxygen in presence of the Brønsted acid. The surface oxygen atoms of γ-Al2O3 were observed to show high affinity for H-abstraction from the oxocarbenium ion to yield the carbenium ion intermediate, which subsequently gave the product butene via a combination of hydride transfer and decarboxylation steps. Higher reactivity of the Brønsted acid promoted γ-Al2O3 surface, was attributed to the direct ring-opening (Ea = 13 kJ/mol) of the surface adsorbed oxocarbenium ion of GVL, leading to the formation of the γ-carbenium ion, which was unlikely to form with the adsorbed GVL structure. In addition, H-abstraction by the surface oxygen from the C5 of adsorbed oxocarbenium ion (Ea = 13 kJ/mol) was calculated to be of lower activation barrier as compared to the H-abstraction from C5 of the adsorbed GVL (Ea = 40 kJ/mol), which may also lead to facile ring-opening in presence of a Brønsted acid on γ-Al2O3. © 2018