Because of its outstanding physical and chemical properties, gamma-valerolactone (GVL) has been identified as a promising renewable platform molecule for the chemical industry. Its synthesis can be performed via many catalytic routes; however, each method results in the formation of a different product mixture, of which components have to be separated before the subsequent utilization of GVL. The use of formic acid (FA) as a hydrogen source for producing GVL by homogeneous-transfer hydrogenation could be one of the most suitable ways, whereas the product mixture could contain FA, GVL, and water. In the present study, the isobaric vapor liquid equilibrium data of FA and GVL was determined. The experimental data were correlated with the Wilson, NRTL, and UNIQUAC models and compared to the ideal vapor pressures as well as modified UNIFAC activity coefficient models. The refractive indexes of the mixture were also determined over the whole concentration range at T = 293.2 and 298.2 K.