In this paper, thermal properties of phosphorus and boron-doped low pressure chemical vapor deposition (LPCVD) polysilicon layers with regard to sensor applications are presented. Thermoelectric coefficient and relative resistance variations of polysilicon are investigated within the temperature range of 293-373 K. Test structures and characterization benches have been developed to obtain measurements with precision of 5%. Ion implantation has been experimented to achieve low electrical resistivities and high Seebeck coefficients. It can be seen that the temperature coefficient of resistance of doped polysilicon is negative, approaches zero, or positive depending on the doping concentration. These results are, to our knowledge, the first reported for such dopant concentrations and are important for design and optimization of high sensitivity thermal sensors using n- and p-doped-LPCVD polysilicon thermopile