This article deals with the structure model-based correction approach for thermal errors at machine tools. Structure models are physically-based models of the thermo-elastic behaviour of machine tools. Input data of the model are technological loads captured in the machine control. The article focuses the experimental validation of the online correction on the example of a demonstrator machine (parallel kinematic). A finite element model with reduced model order is used as structure model. Besides the implementation of the correction approach the parameter adjustment of the model is described. The conducted experiments show that up to 87% of the maximal thermo-elastic error of the ball screw axes of the machine can be compensated with the proposed correction approach.