Detailed local heat (mass) transfer characteristics in rectangular cross-sectioned serpentine ducts with a sharp 180 degrees turn have been measured by the naphthalene sublimation technique, directing special attention to the influence of the flow-inlet condition on the local mass transfer. Two contrasting flow-inlet conditions, a contracted-flow inlet and a uniform-flow inlet, have been tested for three turn clearances in the Reynolds number of 3.5 x 10(4). The distributions of local Sherwood numbers on all the walls of the test ducts are shown in the form of 2-D maps, and the influence of the flow-inlet condition on the local mass transfer characteristics is examined in detail.