Photoinduced electron transfer in two room-temperature ionic liquids, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) and 1-octyl-3-methylimidazolium hexafluorophosphate (OMIM-PF6), has been investigated using steady-state fluorescence quenching of 9,10-dicyanoanthracene with a series of single electron donors. From these fluorescence quenching rates, reorganization energy (lambda) values and k(diff) values can be derived from a Rehm-Weller analysis. In many cases, these fluorescence quenching reactions occur at rates larger than what would be expected based on the Smoluchowski equation. In addition, lambda values of 10.1 kcal/mol and 16.3 kcal/mol for BMIM-PF6 and OMIM-PF6, respectively, have been determined.