The paper gives results of tests of 2 of 11 compounds and several mixtures selected for intensive evaluation from about 40 new synthesized compounds that may serve as environmentally safe and effective refrigerant alternatives over the long term. The two compounds are: 1,1,1,2,3,3-hexafluoropropane (HFC-236ea), a potential alternative for CFC-114; and 1,1,2,2,3-pentafluoropropane (HFC-245ca), a potential alternative for CFC-11. These two compounds have zero ozone depletion potential, low global warming potential, and thermophysical properties closely matching those of the chlorofluorocarbons (CFCs) they may replace. Limited toxicity tests to date reveal no adverse toxic effects. Flammability tests of HFC-236ea and HFC-245ca show the former to be nonflammable and the latter to be marginally flammable depending on humidity and ignition source energy. Both compounds have been shown to be thermally and hydrolytically stable, miscible with the new polyolester lubricants, and compatible with numerous construction materials commonly used in refrigeration.