For the manufacturing of metallic materials at medium and elevated temperatures hot work tool steels are commonly used. To predict the lifetime of these tools it is necessary to characterize the microstructure and its change during the application because the material properties strongly depend on the microstructure. The aim of the present work is the analysis of the precipitation kinetics of carbides with the chemical composition of the hot work tool steel X38CrMoV 5-1 (Böhler W300) during a specific heat treatment. The character, distribution and dimension of the particles were simulated with the simulation software MatCalcTM. For the experimental study steel samples were heat treated in a vacuum furnace. Subsequently the microstructure of the samples was determined by a scanning electron microscope and EDX-analysis to analyse the character and distribution of carbide precipitations. The results of the simulations and of the experimental evaluation were compared and discussed.