The energy‐reflection coefficient &ggr; has been measured for keV protons impinging on Cu, Au, and Pb and helium impinging on Si, Ag, Ta, and Pb. The results are obtained by entirely independent techniques in three different laboratories. They agree within the stated accuracies of 10%. For a given projectile, &ggr; is found to depend on the target material through the Thomas‐Fermi reduced energy &egr; only. Hence, extrapolation to other target materials may easily be performed. The results are in good agreement with those obtained from recent computer simulations.