The geometric parameters of 1, 3-benzodioxol-2-one (BO) and propylene carbonate (PC) was optimized at the B3LYP/6-311++G (d, p) level of density functional theory (DFT) with the polarized continuum models (PCM). The obtained frontier molecular orbital energies and vertical electron affinities indicate that BO is reduced more easily than PC. The transition state (TS) of ring-opening reaction BO-1 --> BO center dot-1 was optimized and confirmed by vibrational frequency analysis and intrinsic reaction coordinate (IRC) method. The bond orders and atomic charge distribution of the stable points along the minimum energy path (MEP) were analyzed using the natural bond orbital (NBO) method at the B3LYP/6-311++G(d, p) level of DFT With these calculated results, the reduction mechanism of BO for the formation of solid electrolyte interface (SEI) film on anode of lithium ion battery can be inferred as: BO + e --> BO-1 --> BO-1 --> center dot center dot center dot --> SEI Film. (C) 2008 Elsevier B.V. All rights reserved.