Open-cage ketolactam fullerenes undergo regioselective hydroamination with phenylhydrazine to afford adducts with 1: 1 and 1: 2 stoichiometry. N-methoxyethoxymethyl (MEM) substitution gave only the 1: 1 adduct, the structure of which was unequivocally evidenced via 2D INADEQUATE (CNMR)-C-13 studies on a C-13 enriched derivative. N-electron withdrawing substituents such as N-tert-butoxycarbonyl (Boc) and benzyloxycarbonyl (BnOCO) result in double hydroamination, providing the 1: 2 adducts bearing 19-membered ring orifices, with concomitant water encapsulation.