Using molecular dynamics simulations, combined with the thermodynamic integration algorithm, we examine the hydration mechanism of C-60(OH)(24) under ambient conditions. We analyze its structural features, dynamics, and hydration free energy. Our results have been compared with a pristine fullerene aqueous system. Despite the number of hydroxyl groups in the fullerenol, its hydration entropy is rather similar to that calculated for C-60. On the other hand, we have calculated a dramatically negative free energy of about -354 kJ/mol for the fullerenol, whereas pure fullerene presents a positive value of about 59 kJ/mol. On this basis, our study indicates that the hydration of C-60(OH)(24) is guided by an enthalpy-driven process. (C) 2011 Elsevier B.V. All rights reserved.