A clean and highly efficient technique has been developed to load diamond anvil cells (DACs) using a small amount of gaseous samples. The loading process consists of two steps. First, gas is condensed on a designated cold surface in a pre-evacuated system; second, the solidified sample is loaded into a DAC at liquid-nitrogen temperature. A hundred milliliters of gas at ambient condition is typically required to produce a solidified sample. The use of solid sample material for DAC loading is beneficial to a clean loading process. We demonstrated this technique by loading isotopically enriched (99.925% -83Kr) krypton into a DAC. 200 ml of this rare and expensive gas were solidified with 99.6% efficiency and almost completely recovered.