Fast atom bombardment mass spectrometry and liquid scintillation counting have been used to study the biodegradation of a novel cationic surfactant in live sludge. The rates of primary biodegradation and the extent of complete mineralization were determined. Furthermore, an intermediate degradation product was identified and its rates of formation and subsequent removal have been established. These data find utility in assessing the environmental safety of the surfactant and the accuracy of various environmental fate models.