Fragment ions from CF α Cl 4−α (α=1–3) have been measured in the soft X-ray region using monochromatized synchrotron radiation and a time-of-flight mass spectrometer. The atomic chlorine ion exhibits the highest yield at most photon energies. Following Cl 2p photoionization, C–Cl bonds are broken frequently, but the process where only the C–F bond is cleaved does not occur, yielding no production of CF α−1 Cl 4−α + . The reverse phenomenon happens at the F 1s photoionization; the rupture of one C–Cl bond does not take place. These findings, site-specific fragmentation, are ascribed to the characteristics of Auger transitions creating valence holes in different molecular orbitals.