The Hugoniot equation of state of pyrolytic graphite of initial density 2.20 g/cm3has been determined to 300 kb for the ``c'' direction. Various explosive techniques for producing the desired pressures, and the optical techniques employed in measuring shock and free‐surface velocities are briefly described. It is found that shock and particle velocity are not linearly related below 70 kb. Above 100 kb, the material is less dense than is powdered natural graphite, as determined by Alder and Christian. The agreement with static compressibility data is satisfactory.