When an axisymmetrical jet hits a target flat surface, the flow stagnates and flows outward in a thin liquid layer. At some location downstream the liquid layer experiences rapid increase of its thickness. This phenomenon is called the hydraulic jump and consists in forming a circular-symmetrical area where the thickness of the liquid film is of by at least one order of magnitude lower than that outside the area. In the paper results of experimental investigations of the hydraulic jump formed by a single-phase water jet and two-phase aerosol jet have been presented. Besides, preliminary experimental results and analytical treatment of heat transfer between the solid surface and liquid layer formed by impinging jet as well as phenomenon of braking down of liquid layer have also been presented.