Horseshoe vortex formation around a vertical flat plate mounted in the water channel is experimentally investigated. In order to demonstrate the development of the horseshoe vortex system in the junction of the horizontal and vertical plates a Particle Image Velocimetry (PIV) and dye visualization techniques were used. Instantaneous and time-averaged velocity vector fields, corresponding streamline topology, vorticity values were analyzed. Boundary layer separation, developing vortices, secondary or counter-rotating vortices, merging of developing and counter-rotating vortices which results in a primary horseshoe vortex system and corner vortex were demonstrated qualitatively and quantitatively. (C) 2009 Elsevier Ltd. All rights reserved.