This document discusses developing phase change materials (PCMs) for military textile applications. PCMs can control body temperature by absorbing or releasing heat during phase changes. The document reviews PCM encapsulation techniques, classifications of PCMs, how PCMs work in textiles, and properties of potential PCMs like polyethylene glycol. PCMs in textiles could provide thermal comfort for military personnel by storing excess heat from the body during temperature rises and releasing it during temperature drops. The document evaluates PCMs like hydrated inorganic salts and polyethylene glycol for military textile applications based on their absorbing/releasing temperatures, latent heat, availability, and toxicity.