An experimental study was performed to investigate the thermal performance of an inclined miniature mesh heat pipe using water-based CuO nanofluid as the working fluid. The study focused mainly on the effects of the inclination angle and the operating temperature on the heat transfer performance of the heat pipe using the nanofluid with the mass concentration of CuO nanoparticles of 1.0 wt%. The experiment was performed at three steady operating temperatures of 40 degrees C, 50 degrees C and 60 degrees C. Experimental results show that the inclination angle has a strong effect on the heat transfer performance of heat pipes using both water and the nanofluid. The inclination angle of 45 corresponds to the best thermal performance for heat pipes using both water and the nanofluid. The present investigation indicates that the thermal performance of an inclined miniature mesh heat pipe can be strengthened by using CuO nanofluid. (C) 2012 Elsevier B.V. All rights reserved.