An experimental study was made of the forced convection freezing characteristics on the convex wall of a return bend with a rectangular cross section. Observations were carried out for duct heights of 17 and 30 mm, a duct width of 300 mm, and a radius of curvature of 159 mm. The convex wall temperature was uniformly maintained below the freezing temperature of water, and the concave wall was insulated. It was found that a stepwise ice layer forms on the convex wall of a return bend and that the step position at the steady-state condition is closely dependent on both the water flow velocity and the cooling temperature ratio.