The compounds of polypropylene (PP) with paraffin wax (PR) as phase change material were fabricated by extrusion melt compounding. The compounds of PR and PP were brittle and showed PR leakage within its melting point range. The maximum 60 weight percent content of the PR was compounded with the polymer. The high amount of paraffin in the polymer plasticized and significantly decreased the melting point of the polymer. The addition of a linear triblock copolymer based on styrene and ethylene/butylene noticeably ameliorated the workability, impact penetration and paraffin retention properties of the compounds. The compounds were further reinforced by carbon fibers and carbon nanotubes that led to an enhancement of their thermal conductivity and heat transfer efficiency. The material structure and thermophysical properties were studied by microscopy and various characterization techniques. The compounds of polymer with PR show phase change effect due to the solid–liquid phase transition of PR within its melting point range. The experimental time vs. temperature curves of the compounds were recorded within the melting range of PR. The experimental curves were compared with the theoretical calculated results. The results were in agreement except small difference that can be attributed to the experimental errors and the assumptions made during theoretical calculations. The manuscript describes the fabrication of shape enduring compounds, with improved thermal, physical, and mechanical properties and their processing by standard techniques, such as extrusion and blow molding. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40164.