The aim of this research is to prepare of a novel form-stable composite phase change materials (PCMs) for the latent heat thermal energy storage (LHTES) in buildings, passive solar space heating or functional fluid by incorporation of eicosane within Polycarbonate (PC) through solution casting technique. The composite PCMs was characterized using scanning electron microscope (SEM) and fourier transformation infrared (FTIR) analysis technique. The results show that the form-stable blends was formed and the maximum encapsulated proportion of eicosane in the composite was 50 wt% without melted PCMs seepage from the composite. In the shape stabilized PCMs, the polymer acts as the supporting material to form the there dimensional network structure and the eicosane acts as a PCMs and disperses in the three-dimensional network structure. Thermal properties, thermal reliability and heat storage or release performance of the composite PCMs were determined by differential scanning calorimetry (DSC), FTIR and thermal cycling test analysis. The melting and freezing temperatures and the latent heats of the composite PCM were measured as 36.2°C-40°C and 62.2 J/g - 63.1 J/g, respectively. The results of DSC, FTIR and thermal cycling test are all show that the thermal reliability of the composite PCMs has an imperceptible change. This conclusion indicates that the blends have a good thermal and chemical stability.