Methods designed for the simultaneous measurement of energy deposition and impulses allowed the study of the equation of state of a refractory material at energy levels exceeding 2000 cal/g. The principle involved consists of comparing the impulse delivered by the material whose thermodynamic behavior is to be determined with that delivered by a material with a known equation of state. The material investigated here is graphite 2239, with specific gravity 1.78. Reference materials are aluminum and sulfur. The experiments were conducted on the Sidonix accelerator, whose electrical characteristics are 1 MV, 0.8 MA, 80 ns.