The objective of this study is to overcome the leakage and low thermal conductivity problems of paraffin as PCMs (phase change materials) for thermal energy storage by impregnating SEBS/paraffin/HDPE FSPCMs (form-stable phase change materials) into metal foam. The form-stable composites were prepared by absorbing paraffin into the network of powder-like styrene-b-(ethylene-co-butylene)-b-styrene (SEBS) triblock copolymer and covering high-density polyethylene (HDPE) on pre-prepared SEBS/paraffin mixture. The composites were characterized by using differential scanning calorimetry (DSC), Scanning electron microscope (SEM), Fourier Transform Infrared Spectrometer (FT-IR), X-Ray Diffraction (XRD) and Hot disk. Paraffin leakage was investigated by accelerated degradation test at 80°C. The melting temperature and latent heat of the composites were determined as 50.56°C and 151.6J/g, respectively. FT-IR results revealed good chemical compatibility among paraffin, SEBS and HDPE. SEM images and XRD test results demonstrated that the paraffin had uniformly dispersed into SEBS. This composite was testified able to keep paraffin from seepage with only 2.39wt% of paraffin loss after 50 thermal cycles test (150h). In addition, the thermal conductivity of SEBS/paraffin/HDPE was 0.272W/mK, which was increased up to 2.142W/mK when copper foam was embedded in the composite. •SEBS/paraffin/HDPE form stable PCM was prepared using a direct impregnation method.•Microstructure and thermal properties of the composites were examined.•The FSPCMs show nearly no leakage under accelerated degradation thermal tests.•The FSPCMs are able to impregnate into metal foam to enhance heat transfer.