Recent shock tunnel experiments have shown an increase in transition Reynolds number with increasing freestream total enthalpy, and linear stability theory, has been used to reproduce the same trends. It was observed that as the freestream enthalpy is increased, the presence of chemical reactions and translational-vibrational energy exchange in the boundary layer becomes increasingly important and a stability code which does not take these effects into account will not give correct disturbance amplification rates. Previous work has shown a significant damping effect of endothermic chemical reactions and thermal energy transfer in boundary layer disturbances. Conversely, exothermic reactions were shown to have a destabilizing effect. This work continues the study of the effect of chemical reactions using the more accurate parabolized stability equations to predict boundary layer transition locations on cones. The results are compared with those from experiments and with the predictions of quasi-parallel linear stability theory.