The thermal decomposition of 1 M LiPF6 in a mixture (1:1 molar ratio) of ethylene carbonate (EC)/dimethyl carbonate (DMC) at 85 degreesC is compared to the reaction between EC/DMC and PF5 gas. Both produce a brown solution and gaseous products. The reaction products from PF5+EC/DMC and 1 M LiPF6 in 1:1 EC/DMC, detected by gas chromatography, are similar. Proton nuclear magnetic resonance provided evidence for the presence of oligoether carbonates in the reaction products.