Experiments on convection heat (mass) transfer in a rectangular channel with a sharp 180-degree turn were conducted to clarify the local heat transfer characteristics. The local mass transfer rate on a long-side wall of the channel whose cross section is 50 x 25 mm was measured using the naphthalene sublimation technique. The results show that the local mass transfer rate is not uniform over the wall and Varies remarkably with the location, especially in the turn and after the turn sections and that the distribution is strongly influenced by the turn clearance of the channel as well as the Reynolds number.