In this paper forced convection from steady rotating circular cylinder in a cross stream of nanofluid is theoretically investigated. The nanofluid is formed by adding Nanometric particles of copper to water. The flow and energy governing equations are solved using Fourier spectral method. The main influencing parameters on flow and thermal fields are Reynolds number, particles volume fraction and the cylinder speed ratio (peripheral velocity of rotating cylinder/ uniform free stream velocity). The Reynolds number is considered up to 200, the volume fraction of nanoparticles is considered up to 0.05 while the cylinder speed ratio is considered up to 1. The effects of Reynolds number, solid particle volume fraction and cylinder speed ratio on both flow and thermal fields are considered. The study has shown very good agreement with the previous results in the literature for cases of fixed and rotating cylinder in cross stream of a Newtonian fluid. The study has also shown that increasing of volume fraction of nanoparticles increases the heat transfer rate for both fixed and rotating cylinder while increasing the cylinder speed ratio for the given range of parameters is found to decrease heat transfer rate. Also, the study has shown that increasing nanoparticles volume fraction increases drag coefficient for stationary cylinder, while increasing nanoparticles volume fraction decreases drag coefficient for low speed ratios, has no significant effect on lift coefficient, and has a slight increasing effect on Strouhal number. Also, increasing speed ratio α decreases both lift and drag coefficient (for low speed ratios).