Organic-inorganic hybrid materials made from polydimethylsiloxane (PDMS) have been studied as encapsulation materials for high-power devices because of their high dielectric strength, high heat resistance, and flexibility when compared to conventional elastomers. To improve the heat-resistant property, hybrid materials made from two PDMS components, PDMS terminated with silicon alkoxide Si5O4(OC2H5)(12) (A-PDMS) and PDMS terminated with ethyl-acetoacetate-modified titanium alkoxide Ti(OCH2CH(C2H5)C4H9)(4) (T-PDMS), were prepared. We found that the heat-resistant property of a hybrid material could be improved by adjusting the molar ratio between A-PDMS and T-PDMS. After heat treatment at 250 degrees C for 1,000h, the hardness and weight loss of the hybrid material made from A-PDMS and T-PDMS were under 60 degrees (on an Asker C durometer) and under 5.0%, respectively. The excellent long-term thermal stability of the hybrid material made from A-PDMS and T-PDMS can be attributed to the improved homogeneity of inorganic clusters and the decrease in unreacted functional groups in hybrids by using T-PDMS as a raw material.