The impinging turbulent slot jet was investigated experimentally using tomographic particle image velocimetry technique. The jet Reynolds number was considered equal to 9000 and the nozzle to plate distance was 10 times the width of the nozzle. The mean flow and turbulent statistics were evaluated at different cross-sections. Then, the dominant three-dimensional structures of the turbulent flow were identified using the Proper orthogonal decomposition (POD) method, and the contribution of different energy modes to the total energy was determined. It is observed that the first 40 POD modes can be considered as the dominant flow modes which contain about 89 % of total kinetic energy of the flow. Also, horseshoe form structures were observed in some POD modes on both sides of the jet central plane. Finally, three-dimensional vortex structures were specified using vorticity, Q and λ2 criteria, and compared with each other. © 2017, The Korean Society of Mechanical Engineers and Springer-Verlag GmbH Germany, part of Springer Nature.