Experiments on wing wall were carried out in a circulating fluidized bed pilot plant of 1000 mm x 500 mm in cross section and 5000 mm in height operated at room temperature. A wing wall (918 mm x 500 mm) was hung at two different positions in the riser. A downward solids flow was noticed when the wing wall was located at the top of the riser, but no downward solids flow was observed on its surface when the wing wall is placed 1300 mm below the roof. For a given operating condition, the heat transfer coefficient on the wing wall was higher when it was placed at the top of the riser than when located at mid-height. The difference in heat transfer between water wall and wing wall, as observed in the present experiment, is similar to that noted in commercial boilers.