Silica fume has been used as a replacement for cement, due to its high early compressive strength, high tensile and flexural strength, high bond strength, and enhanced durability of concrete. This study examined enhanced thermal performances of silica fume by incorporating organic PCMs, for applying to concrete. Three kinds of organic PCMs were incorporated into the silica fume. The silica fume/PCM composites were prepared by the vacuum impregnation method. Because silica fume has a high porous structure compared to cement, it is useful to incorporate the PCM, to enhance its thermal storage performance. The characteristics of the composites were determined by using SEM, DSC, FTIR and TGA. SEM morphology showed the micro-structure of silica fume/PCM. Also, thermal properties were examined by DSC and TGA analyses; and the chemical bonding of the composite was determined by FTIR analysis.