Forced convective heat transfer with nanofluid flow over a circular cylinder has been numerically studied using the single- phase dispersion model. The cylinder has a constant wall temperature of 350 K and is exposed to a free stream of nanofluid (Al2O3–H2O) at ambient temperature for Reynolds number in the range of 20–160. A steady-state analysis uses a 2-D domain, and governing equations are solved using a finite volume method based on the SIMPLE algorithm. Effect of volume fraction (0.05 < ϕ < 2) and Reynolds number on the heat transfer characteristics are studied. Nanofluid exhibits a higher heat transfer rate than base fluid for all volume fractions and Re. The highest Nusselt number is obtained near the front stagnation point and decreases toward the rear stagnation point. It is observed that for a given volume fraction, the heat transfer enhancement ratio increases up to Re = 120, and then there is no significant change.