Experimental investigation on hydrodynamic and single phase heat transfer performance in a microchannel was the main aim of the present study. Experiments were performed in a single circular microchannel having internal diameter of 0.79mm and 440mm length. Solution of Poly(vinyl alcohol) in deionized (DI) water as a non-Newtonian fluid and non-Newtonian nanofluid with volumetric concentration of 0.1% SiO 2 nanoparticles were used as working fluids in the experiments. The thermal conductivity of DI-water and the non-Newtonian fluid and non-Newtonian nanofluid was measured at bulk temperature. Results shown that thermal conductivity of non-Newtonian fluid enhanced about 11% in comparison with DI-water which was related to the presence of hydroxyl groups in non-Newtonian fluid. Also the thermal conductivity of non-Newtonian nanofluid enhanced about 18% compared to non-Newtonian fluid which was related to the effects of Brownian motion and formation of Molecular layer around nanoparticles. Experiments for DI-water were performed in order to validate experimental setup used in this study. Measurements were in good agreement with published data. The measured friction coefficients for deionized water were in good agreement with Hagen-Poiseuille law while the non-Newtonian fluid and non-Newtonian nanofluid friction coefficients exhibit a significant positive departure from the Hagen-Poiseuille law. The convective heat transfer coefficient of non-Newtonian fluid flow enhanced about 19% compared to DI-water and the convective heat transfer coefficient of non-Newtonian nanofluid flow enhanced about 17% in comparison with non-Newtonian fluid which was related to the effects of Brownian motion, formation of Molecular layer around nanoparticles and thermophoresis phenomena. Keywords: micro-channel; Heat transfer; non-Newtonian fluid; non-Newtonian nanofluid.