Young's modulus and the shear modulus of grade SA‐25 molded graphite and grade AUF extruded graphite were measured as functions of temperature in the range from 25°C to 2000°C. In the case of the extruded material, variations of the two moduli with position and direction relative to the axis of extrusion were also investigated. The moduli were found to increase with temperature, a behavior in contrast with that exhibited by most materials. Maxima in the low frequency shear modulus values and increases in the internal friction of both graphites observed in the range from 1550–1750°C may possibly be interpreted in terms of grain boundary relaxation. The bulk modulus and Poisson's ratio at room temperature were calculated from the data for the nominally isotropic SA‐25 graphite to be 6×1010dynes/cm2and 0.27, respectively.