Abstract: A differential scanning calorimeter based on the heat leak principle having a reference measuring cell and a sample measuring cell symmetrically seated within a copper heat sink surrounded by an isothermal shield. Each measuring cell includes a cylindrical stainless steel ampoule which contains a test substance, a honeycombed aluminum cell frame which supports the ampoule, and a pair of thermopiles which are placed between the aluminum cell frame and the copper heat sink and which measure the temperature difference between the two. A plurality of resistive heating elements wired in series are applied to different sections of the heat sink and the isothermal shield, each heating element having a resistance respectively proportional to the heat capacity of the heat sink sections and the shield. A common current is then passed through the heating elements, thus producing a highly uniform positive temperature scan with a minimum of residual temperature gradients existing within the heat sink.