Perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), persistent organic pollutants, were photodegraded by ultra-violet light irradiation in water, alkaline 2-propanol (IPA), water including H(2)O(2), and water including both H(2)O(2) and Fe(2+), and the photodegradability in each condition was compared. F(-) and SO(4)(2-) were generated with the PFOS decomposition and F- was generated with the PFOA decomposition. The degradation ratio of PFOS was lower than that of PFOA in each condition. The photodegradability of PFOS and PFOA depended on the sample condition. Effective degradation was observed in alkaline IPA for PFOS, and in water for PFOA. Added H(2)O(2) increased the photodegradability of PFOS. With the photo-Fenton reaction, although the degradation ratio of PFOA reached to 100%, that of PFOS was only 28.6%.The C-F bond dissociation in PFOA molecular progressed slowly in water, however the process was accelerated under photo-Fenton condition. In PFOS, on the other hand, C-F bond dissociation was suppressed to progress under photo-Fenton condition.