In this study, thermal energy storage cement-based composite (TESC) was developed by incorporating paraffin/diatomite (DP) composite phase change material (PCM). Paraffin/DP composite PCM was firstly fabricated at mix proportion (paraffin: DP) of 0.9:1.0. Scanning electron microscope (SEM) and Fourier transform infrared (FT-IR) results show that paraffin can be well impregnated into DP pores and has good compatibility with it. Differential scanning calorimetry (DSC) results reveal that paraffin/DP composite PCM has melting temperature and latent heat of 41.11. °C and 70.51. J/g, respectively. Good thermal stability is observed for this fabricated composite PCM by using thermogravimetric analysis (TGA) method. Furthermore, paraffin/DP composite PCM was incorporated in cement-based composite at 10%, 15%, 20% and 30%, by weight of cement. It is found that in comparison with control normal cement-based composite, maximum reductions on 28-day compressive strength and flexural strength, drying shrinkage strain and thermal conductivity by incorporation of paraffin/DP composite PCM are 48.7%, 47.5%, 80.7% and 33.6%, respectively. Good thermal energy storage performance of TESC is clearly suggested by results of specific heat capacity test and heating test. © 2013 Elsevier Ltd.