We devised an apparatus and technique for loading diamond‐anvil cells with gases at high pressure. Cells were filled quickly and conveniently at room temperature with helium and hydrogen isotopes to initial densities exceeding those of the normal liquids. We report preliminary values of4He and D2melting points based on the ruby pressure scale and compare them with extrapolations from our earlier melting curves measured to 20 kbar in a piston‐cylinder device. Our filling procedure now makes it possible to use4He as a pressure medium in diamond cells. The technique is also useful for loading cells with gaseous mixtures.