A high pressure differential scanning calorimeter for low temperature investigations is described. It allows the measurement of thermodynamic properties of substances over wide ranges of temperature and pressure, e.g., between 100 and 450 K at normal pressure and between 100 and 300 K at 4 kbar. Up to now the calorimeter has been used for the determination of transition enthalpies and transition temperatures of some plastic crystals up to 1500 bar from which other properties, e.g., transition entropies and transition volumes, can be calculated.