The metals aluminum, iron, nickel, and types 304 and 316 stainless steel have been doped with helium by allowing dissolved tritium to undergo radioactive decay. Helium concentrations below 1 atomic ppm were produced. Using high−sensitivity, mass−spectrometer techniques, helium release has been observed during isochronal and isothermal anneals. At least two release mechanisms are obvious, their respective gas releases occurring at widely separated temperatures.