A new composite phase change material was fabricated by adding 0.05, 0.1, 0.15, and 0.2 wt.% CuO nanoparticles into lauric acid. SEM analyzed morphology; X-ray diffraction characterized crystalline structure. Phase change properties (temperature, latent heat) were determined via DSC. Thermal conductivity was evaluated using a laser flash analyzer, and thermal reliability was assessed over long periods. © 2022 Elsevier B.V., All rights reserved.