An oxidative radical photo-addition of mono N-substituted piperazines to fullerene was systematically investigated. Reactions of C60 with piperazines hearing bulky electron-withdrawing groups (2-pyridyl, 2-pyrimidinyl) were found to be the most selective and yielded C60(amine) 4O as major products along with small amounts of C 60(amine)2. In contrast, interactions of fullerene with N-methylpiperazine and N-(tert-butoxycarbonyl)piperazine were found to have low selectivity due to different side reactions. Tetraaminofullerene derivative C60(N-(2-pyridyl)piperazine)4O was found to react readily with organic and inorganic acids to yield highly water-soluble salts (solubility approximately 150mg mL-1). In contrast. C60,(N-(2- pyrimidinyl)piperazine)O4 undergoes hydrolysis under the same conditions and results in a complex mixture of compounds with an average compositions. of C60(N-(2-pyrimidinyl)piperazine)2(OH) 2O. Radical photoaddition of N-(2-pyridyl)piperadne to fullerene derivatives can he used as a facile route for their transformation into water-soluble compounds. Two model fullerene cycloadducts (a methanofullerene and a pyrrolidinofullerene) were easily converted into mixtures of regioisomers of A = C60(B-(2-pyridyl)piperazine)4,O (A = cyclic addend) that give highly water-soluble salts under acid treatment.