Among the most versatile polymers with applications spanning from high-tech biomedical to common daily use are the polyurethane thermoplastic elastomers. The 2-phase morphology of thermoplastic polyurethanes (TPUs) enables tailoring of processability and properties in such systems. Nonetheless, there is still very large potential to enhance the properties of TPUs in nanocomposite systems. In recent years, carbon nanotubes (CNTs) have attracted significant attention as the filler of choice for advanced polymer composites due to their high aspect ratio and remarkable mechanical, thermal and electrical properties. However, due to strong interparticle interactions, individual CNTs tend to form larger agglomerates with inferior properties. Difficulties in uniformly dispersing CNTs have resulted in sub-par material properties as compared with what could theoretically be achieved for well-dispersed systems. Using in-situ polymerization to obtain CNT/TPU nanocomposites may provide an avenue for obtaining well dispersed nanofillers into the TPU matrix. The presence of CNTs during polymerization will most likely affect the reaction kinetics. In this study we use chemorheology to investigate the effect of CNTs on the kinetics and degree of polymerization for a system comprising Polycaprolactonediol and 1,4- Phenyldiisocyanate (PPDI). We employ an empirical chemo-viscosity model to elucidate the effect of CNTs on reaction kinetics. We also study the effect of temperature on reaction rate and degree of polymerization for the neat TPU and systems containing various CNT concentrations. Keywords: Chemorheology, Thermoplastic polyurethane, CNT nanocomposite.