Density functional theory (DFT) calculations on three lower energy isomers of C50 were carried out at the B3LYP/6-31G* level. Of the three isomers, two have D5h symmetry (a singlet state and a triplet state) and the other one has D3 symmetry. The optimized configurations and electrostatic potential distributions have been obtained. The calculated results show that potential minima Vmin(r) inside the sphere occur at the center of the sphere. The most negative value of the effective Mulliken atomic charge and the largest regions with the most negative MEP outside the sphere are localized in the neighborhood of pentagon-pentagon vertex fusions. They constitute the most probable active sites in chemical reactions. Our results offer a possible explanation for protonation and alkylation of C50 fullerene. Density functional theory (DFT) calculations on three lower energy isomers of C50 were carried out at the B3LYP / 6-31G * level. Of the three isomers, two have D5h symmetry (a singlet state and a triplet state) and the other one has The optimized configurations and electrostatic potential distributions have been obtained. The calculated results show that potential minima Vmin (r) inside the sphere occur at the center of the sphere. The most negative value of the effective Mulliken atomic charge and theially regions with the most negative MEP outside the sphere are localized in the neighborhood of pentagon-pentagon vertex fusions. They constitute the most probable active sites in chemical reactions. Our results offer a possible explanation for protonation and alkylation of C50 fullerene.