This paper focuses on the study of thermal performances of MOS transistors for bolometer applications. Series of measurements have been conducted to obtain TCC (Temperature Coefficient of Current) versus gate voltage and temperature curves. The measurements were confronted to atlas simulations, and showed that in the subthreshold region the TCC ranges from 4 %IK all the way to 9%1K. It was also determined that gate length does not have an influence on the TCC until short channel effects factor in.