From Sulfolobus solfataricus, a sulfur-oxidizing thermophilic member of archaebacteria, three unusual benzothiophenquinones were isolated. Detailed NMR studies on these quinones, including multipulse mono-dimensional and two-dimensional techniques, were performed to obtain carbon and proton assignments, one-bond, geminal and vicinal coupling constants and T1 relaxation times. This report extends the known quinone composition of thermophilic archaebacteria and further supports the concept that these biomolecules can serve as a useful chemotaxonomic tool.