Nanoencapsulation of phase change materials are receiving increasing attention because of enhanced thermal conductivity and thermal capacity as well as ease of incorporation into the matrix for a wide range of applications. In this work, we have developed a simple and efficient approach to fabricate nanoencapsulated organic phase change (NEPCM) particles in water via coacervation using an amphoteric and temperature-sensitive polymer. The chitosan-co-poly(methacrylic acid) (CTS-co-PMAA) copolymer plays dual functions as an emulsion stabilizer and a shell material. The fabrication steps involve emulsion formation, followed by coacervation to form particle shell through adjusting solution pH, and finally rigidization of the shell via glutaraldehyde cross-linking. This method achieves high encapsulation efficiency (up to 84%) with a PCM content of 66%, high thermal capacity (LHs 165 J g(-1) and LHm 169 J g(-1)), and high thermal cycling stability over 100 phase change cycles.