Differential scanning calorimetry (DSC) was used to compare the thermal stability of charged cathodes in 1M LiPF6 EC/DEC electrolyte. Seven possible cathode materials for lithium-ion batteries (LiCoO2, LiNiO2, LiNi0.8Co0.2O2, Li1+x Mn2−x O4, LiNi0.7Co0.2Ti0.05Mg0.05O2, Li[Ni3/8Co1/4Mn3/8]O2, and LiFePO4) were tested under the same conditions. Welded stainless steel DSC sample tubes, that ensured no weight loss during analysis, were used for these measurements, making them reliable. A consideration of these DSC results and the known electrochemical properties of the cathodes may assist the selection of the most suitable lithium-ion cathode material for use in a particular application.