A programmable SIMS instrument was developed and used to perform accurate depth profiling analyses of an activated Be–Cu alloy. The instrument offers information at every 75 Å under typical ion bombarding conditions, 0.3 μA of 8 keV 40Ar+. Analytical results showed that the BeO of 10 wt. % or more is formed on the surface, which is composed of a reasonably homogeneous BeO layer with a thickness of the order of 300 to 500 Å. The BeO spreads out toward the inner layer and reaches 5000 Å or more. The Be concentration on the surface is less than 0.2 wt. %, but at a depth of more than 3000 Å it aapproximates the concentration of the mother body, about 1.9 wt. %.