Densities of levulinic acid, ethyl levulinate, butyl levulinate, furfural, and furfuryl alcohol have been measured using a high-pressure, high-temperature vibrating tube densimeter system over a temperature range from 283.15 to 338.15 K and a pressure range from 0.1 to 60.0 MPa. In the case of levulinic acid, the temperature range was from 308.15 to 338.15 K The experimental densities have been satisfactorily correlated with the temperature and pressure using the TRIDEN equation. Finally, from the measured densities, some thermodynamic properties, isobaric thermal expansion and isothermal compressibility, have been calculated.