The thermodynamic properties of n-hexane adsorption on MgO(100) were determined using high-resolution volumetric adsorption isotherms in the temperature range 195-255 K. Two distinct layering transitions are observed in the isotherms. The isotherms are used to calculate the two-dimensional compressibility, the differential enthalpy and entropy, the heat of adsorption, and the isosteric heat of adsorption. Neutron Diffraction is used to identify where melting of the n-hexane monolayer takes place.