This master´s thesis deals with the determination of the stiffness of a preloaded double-row bearing with an angular contact in the relevant conditions. The introduction describes the basic knowledge about double row angular contact bearings and the relationship between internal clearance, preload and other effects on stiffness. An overview of studies dealing with bearing stiffness and an overview of devices used for experimental stiffness determination is given. Subsequently, the solution itself is described, in which the theoretical calculation of the bearing stiffness was performed first. To determine the experimental values, it was necessary to design and construct experimental device for testing the bearing in the relevant conditions. The effect of material and temperature on the stiffness of the bearing was determined from the measured data and theoretical calculations. The result of this thesis is a functional device, which was used to test the bearing in the thermal chamber.