An improved buffer rod‐specimen unit is described for measuring longitudinal wave velocities in solids at temperatures up to 350°C. The method is particularly useful in determining elastic moduli of single crystals since very small path lengths in any prescribed direction can be employed. The use of molten metals to provide coupling at still higher temperatures is discussed.Two methods involving mode conversion at an impedance discontinuity are described for measuring shear wave velocities. Application to crystals of cubic symmetry is detailed, with a note on possible extension to less symmetrical crystals of any orientation.Data for fused silica and single crystal germanium are listed for temperatures up to 300°C in illustration of the methods described.