In terms of density functional theory combined with statistic mechanics computations, we investigated a dimetallic sulfide endohedral fullerene Sc2S@C76 which has been synthesized without any characterization in experiments. Our theoretical study reveals that Sc2S@Td(19151)‐C76 which satisfies the isolated‐pentagon rule (IPR) possesses the lowest energy, followed by three non‐IPR structures (Sc2S@C2v(19138)‐C76, Sc2S@Cs (17490)‐C76, and Sc2S@C1(17459)‐C76). To clarify the relative stabilities of those isomers at high temperatures, enthalpy–entropy interplay has been taken into consideration. Calculation results indicate that three species Sc2S@Td(19151)‐C76, Sc2S@C2v(19138)‐C76, and Sc2S@C1(17459)‐C76 have noticeable molar fractions at the fullerene‐formation temperature region (500–3000K), and the Sc2S@C1(17459)‐C76 with one pentagon pair becomes the most predominant isomer above 1800 K, suggesting that the unexpected non‐IPR structure is thermodynamically favorable at elevated temperatures. In addition, the structural characteristics, electron features, UV‐vis‐NIR adsorptions, and 13C NMR spectra of those three stable structures are introduced to assist experimental identification and characterization in future. © 2014 Wiley Periodicals, Inc.