The aim of this paper is to study the interest of Thermoelectric Power (TEP) measurement for carbon in solid solution (C-ss) quantification and show its applicability for strain aging study in Bake Hardening (BH) steels. First we show that the TEP, if used with an appropriate protocol, can be a quantitative technique to evaluate C-ss in steel. Compared to Internal Friction, TEP is less sensitive to metallurgical parameters as alloying elements or texture. Then this quantitative method has been applied for the determination of BH-C-ss correlation. It reveals a correlation slightly translated compared to BH-C-ss correlation determined using internal friction which implies to reconsider the relation between BH and low C-ss content.