Because of the outstanding physical and chemical properties of biomass-originated gamma-valerolactone (GVL), it has been characterized as a promising alternative platform molecule, which can be utilized as an oxygenate in fuels and green solvents. Herein, the isobaric vapor-liquid equilibrium (VLE) of GVL and toluene, which was selected as a representative of aromatic hydrocarbons, was investigated at p = 101.3 and 50.7 kPa. The experimental data were correlated with Wilson, NRTL, and UNIQUAC activity coefficient models. The temperature-dependent vapor pressure of toluene was additionally determined and correlated with the three-parameter Antoine and Clark-Glew equations. All the applied models were found suitable for representing the VLE data. It was found that the toluene (1)-GVL (2) mixture shows a positive deviation from Raoult's ideality as well as from the UNIFAC prediction at both pressures.