Energy storage is a useful tool to increase energy efficiency and energy savings. Solid-Liquid phase change materials (PCMs) are used in latent heat thermal energy storage systems. Plastics are currently used as encapsulate materials with PCM, but previously a compatibility test should be made to ensure long term stability. It is not possible to find experimental studies of organic PCM migration in plastics in the literature. The main objective of this work is an experimental study of the compatibility of some PCMs typically used for thermal energy storage with a melting temperature around 22°C and some plastic materials currently used as encapsulate materials. The PCMs tested are molecular alloy C16-C18, RT20, RT25, RT26, and TH24, and plastic materials tested are PP, LDPE, HDPE, and PET. As a consequence of the results, the best plastic to be used with each PCM and combinations that should be avoided are chosen.