A series of novel capric-palmitic-stearic acid ternary eutectic/polyacrylonitrile/carboxyl purified multi-walled carbon nanotubes (CA-PA-SA/PAN/MWNTs-COOH) form-stable phase change composite fibrous membranes (PCCFMs) were fabricated by electrospinning and physical absorption methods. In these form-stable PCCFMs, the CA-PA-SA ternary eutectic was served as phase change material for thermal energy storage, and the loaded MWNTs-COOH was acted as thermal conductivity enhancement filler to improve heat transfer rates, as well as electrospun PAN/MWNTs-COOH fibrous membranes with different weight fractions of MWNTs-COOH (i.e., 5, 10, and 20 wt%) were used as supporting materials to provide structural strength and prevent liquid leakage of melted CA-PA-SA ternary eutectic. The morphological structure and thermal performances were investigated and analyzed. The images of scanning electron microscopy showed that the CA-PA-SA ternary eutectic was uniformly embedded and dispersed into the three-dimensional porous network structure of electrospun PAN/MWNTs-COOH fibrous membranes. Thermal performance tests suggested that the melting and freezing times of the CA-PA-SA/PAN/MWNTs-COOH form-stable PCCFMs with the addition of 10 wt% MWNTs-COOH were significantly shorten by about 52% and 56% in comparison with those of the CA-PA-SA/PAN form-stable PCCFMs. Their phase change temperatures and enthalpies were about 7 degrees C-32 degrees C and 130-138 kJ/kg, respectively. POLYM. ENG. SCI., 59:E403-E411, 2019. (c) 2018 Society of Plastics Engineers