Electronic properties of fullerene C-60 and its derivatives C60X2, where X = H, C4H9, (CH2)(n) COOH (n = 3, 5, 7), and C4H8SH, are investigated by the density functional theory (B3LYP/6-31+G*) aiming at efficient design of new organic semiconductors. Concerning electron-injection and electron-transport properties of the materials, LUMO energy, adiabatic electron affinity, and reorganization energy are discussed. The electronic properties of C60X2 are considerably different from those of C-60. They are determined by the addition position of X and not by the chemical nature of X. Generally, C60X2 is predicted to be superior to C-60 in the electron-injection property but to be inferior in the electron-transport property. (C) 2009 Elsevier B.V. All rights reserved.