In the polymer industry, neutral phosphate esters are used as flame retardant plasticizers. As lubricants, they find wide use as fire-resistant functional fluids and as antiwear additives. In all these applications, thermal properties like degradation, oxidation, and volatility play a critical role in their performance. This study evaluates degradation and weight loss (volatility) characteristics of commercial phosphate esters in a nitrogen atmosphere, and is a follow-up to previous work performed in oxygen. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques have been used to evaluate thermal properties. Decomposition aspects in nitrogen relative to oxygen are compared and discussed in this paper.