Halocarbons of the structure CF3CF2CH2X, wherein X is either F or Cl or mixtures thereof prepared by: contacting at least one 2-fluorochloropropane with hydrogen fluoride in a first fluorination step in the gas phase or liquid phase under substantially anhydrous conditions, in the absence of added catalyst to partially fluorinate said 2-fluorochloropropane; contacting said partially fluorinated 2-fluorochloropropane with at least the stoichiometric molar equivalent of hydrogen fluoride under substantially anhydrous conditions, in the presence of at least one fluorination catalyst in a second fluorination step; removing said reaction products from contact with said catalyst, and isolating a substantial yield of at least 1,1,1,2,2,3-hexafluoropropane or 1,1,1,2,2, penta-3-chloropropane, or mixtures thereof, respectively.