Forced convection in an open-ended vertical eccentric annulus with different eccentricities has been experimentally studied with several heat fluxes and inlet air velocities. Constant heat flux outer tube and insulated inner tube boundary conditions were used. The wall temperature of the outer tube was measured along the length for different eccentricities. Results indicate that with the increase of eccentricity, the convection heat transfer coefficient increases. Also, as the Reynolds number is increased a crest is formed in the temperature variation along the length. An empirical relation is derived for the Nusselt number as a function of the Reynolds number and eccentricity. (C) 2009 Elsevier Ltd. All rights reserved.