Vibrationally excited CF2ClCHFC2H5(CF2ClCHFC2D5) molecules were prepared in the gas phase at 300 K with approximate to 93 kcal mol(-1) of energy by recombination of CF2ClCHF and C2H5 or C2D5 radicals. Three unimolecular reactions were observed. 1,2-ClF interchange converts CF2ClCHFC2H5(CF2ClCHFC2D5) into CF3CHClC2H5(CF3CHClC2D5), and subsequent 2,3-ClH (ClD) elimination gives CF3CHCHCH3 (CF3CHCDCD3). 2,3-FH(FD) elimination gives cis- and trans-CF2ClCHCHCH3 (CF2ClCHCDCD3), and 1,2-ClH elimination gives CF2CFCH2CH3 (CF2CFCD2CD3). The experimental rate constants for CF2ClCHFC2H5 (CF2ClCHFC2D5) were 1.3 x 10(4) (0.63 x 10(4)) s(-1) for 1,2-FCl interchange and 2.1 x 10(4) (0.61 x 10(4)) s(-1) with a trans/cis ratio of 3.7 for 2,3-FH(FD) elimination. The 1,2-ClH process was the least important with a branching fraction of only 0.08 +/- 0.04. The rate constants for 2,3-ClH (ClD) elimination from CF3CHClC2H5 (CF3CHClC2D5) were 1.8 x 10(6) (0.49 x 10(6)) s(-1) with a trans/cis ratio of 2.4. Density functional theory was used to compute vibrational frequencies and structures needed to obtain rate constants from RRKM theory. Matching theoretical and experimental rate constants provides estimates of the threshold energies, E-0, for the three reaction pathways; 1,2-FCl interchange has the lowest E-0. The unimolecular reactions of CF2ClCHFC2H5 are compared to those of CF2ClCHFCH3. Both of these systems are compared to CH3CHFC2H5 to illustrate the influence of a CF2Cl group on the E-0 for FH elimination.