[en] Acoustic techniques developed to allow determination of the elastic moduli of structural materials of interest to the Liquid Metal Fast Breeder Reactor and the High Temperature Gas Reactor programs are described. Measurements of the elastic moduli of a number of different materials were performed at temperatures from 20 to 1100⁰C. A two-step process was required to complete the measurements. First, the acoustic velocities were accurately measured using bulk samples at room temperature. Wire samples were then used to obtain elevated-temperature measurements by using a magnetostrictive transducer and an automatic data acquisition system. A computer was used to calculate the moduli and plot the data. A detailed summary has been made of the sources of error and a calculation of the precision of the measurements is given