Hydrofluorocarbons (HFCs) and hydrofluoroethers (HFEs) are considered to be potential replacements for chlorofluorocarbons (CFCs). The values of heat of formation have been calculated by using both the bond additivity corrected MP2 method (BAC-MP2/6-31G**) and atom additivity corrected MP2 method (AAC-MP2/6-31G**) for moderate sized HFCs and HFEs for which the literature values are not available. The reliability of the calculated values by these methods has been examined by comparing them with the values obtained with G2 and G2MP2 methods as well as with the literature values for a set of 42 simpler molecules. (C) 2002 Elsevier Science B.V. All rights reserved.