Synthesis of novel hydrophilic fullerenols was described. The reaction involved an oleum-induced oxidative sulfation of the C70 molecules with a product yield of 86%. The rate of fullerene sulfation was accelerated either moderately or greatly by the addition of P2O5 or SeO2, respectively. Hydrolysis of the resulting polycyclosulfated C70 in H2O at 80°C afforded fullerenols in a yield of more than 72%. The negative ion MALDI-TOF mass spectrum of fullerenols showed a well-defined pattern of ion fragmentations with a nearly constant, consecutive weight increase in 17 mass units from the mass of C70. Detection of a molecular ion at m/z 1146 was indicative for the composition of fullerenols as octadecahydroxyfullerenes, containing 18 hydroxy addends per C70 cage. That correlates the structure of their polycyclosulfated precursors to nonacyclosulfated fullerenes, C70(SO4)9.