Novel high density polyethylene (HDPE)/SiO2 hybrid materials were prepared by the sol–gel process using tetraethoxysilane (TEOS). HDPE and synthesized HDPE-g-vinyl trimethoxysilane (VTMS) through melt grafting method was used as the raw material. The structure and thermal, mechanical properties of hybrid materials were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), simultaneous thermogravimetric (TG), differential thermal analysis (DTA), and tensile tests, respectively. Silica phase in the HDPE-g-VTMS hybrids showed a network structure and nano-scale size. The covalent bonds between organic and inorganic phases were introduced by the HDPE-g-VTMS bearing trimethoxysilyl groups, which underwent hydrolytic polycondensation with TEOS. The thermal stability and mechanical properties of HDPE-g-VTMS hybrids were obviously improved by embedded silica networks. It was found that the silica content in the HDPE-g-VTMS hybrid material was linearly increased with the TEOS dosage. The formation of the HDPE-g-VTMS hybrid was beneficial for enhanced mechanical strength and thermal stability, in comparison with the neat HDPE. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014, 131, 39891.