Materials testing of S-65-B grade beryllium has been conducted in order to evaluate the use of this material for limiter surfaces in the ISX-B and JET tokamaks. Selected thermal and mechanical properties were measured at temperatures up to 700 °C. These measurements revealed that S-65-B has exceptionally high ductility (up to roughly 50% elongation) at temperatures expected in normal operation of a beryllium limiter. Thermal fatigue tests under conditions relevant to limiters in ISX-B and JET were also performed using the Sandia National Laboratories Electron Beam Test System (EBTS). Results from these tests were compared to calculated results based on elastic-plastic finite element stress analyses. It was concluded from these tests and analyses that properly designed beryllium limiters should survive normal operation in ISX-B, JET, and similar devices without serious structural failure. Some degree of surface cracking can be expected, however, unless cyclic plastic deformation at the heated surfaces can be adequately controlled by careful design of the limiter.