Aluminium cylinder heads and cylinder blocks employed in combustion engines have to withstand high mechanical and thermal loads in service. High cooling rates are therefore needed in those critical parts in order to achieve fine-grained sound castings. Mainly casting processes using metallic dies with internal water cooling are suitable for the production of these components. Proper temperature control of the die reduces thermal fatigue, shortens cycle times, and results in consistent good quality. The effect of water cooling in gravity die casting processes for the production of aluminium cylinder heads is examined in the course of this work. A thermal analysis of the ground plate of a core package system is carried out in the first series of experiments using four different cooling arrangements. The second series consists of test castings with the same four cooling arrangements. Cooling curves are obtained from thermocouples at defined positions in the ground plate and in the castings. The experimental results are used to fit the boundary conditions in a finite difference simulation of both series of experiments. Thus, the heat transfer coefficients between adjacent parts of the ground plate and between the die steel and the melt are determined. Furthermore the work contains an overview of different means of cooling in die casting.