Rene 65 is a currently widely unexplored nickel-base alloy developed by General Electric, which should show improved temperature properties [1]. This thesis focuses on the investigation of pre-existing data sets of a recently finished research project and parameterization of a material model for Rene 65. For this purpose, typical semi empirical microstructure models out of literature were used, adapted and applied to the new alloy. Data from forming tests such as Rastegaev and Doublecone-Upsetting were examined and processed. The tests were carried out in a forging area common to René 65. Experiments with effective strains between 0.1 and 0.6, strain rates of 0.5 s-1, 5 s-1, 50 s-1 and forming temperatures of ST-60°C, ST-30°C, ST, ST+30°C and ST+60°C were carried out. The evaluation of these data set showed, that additional data with higher effective strains are necessary in order to get a parameter assessment with a sufficient correlation coefficient. Thus new experiments have been planned and preformed up to an effective strain of 0.9. Furthermore, the characteristics of the forging equipment used at the project partner voestalpine BÖHLER Aerospace GmbH & co KG (BSTG) and data of an early development stage Rene 65 material were considered during planning. The new tests were performed at strain rates of 0.1 s-1, 5 s-1, 20 s-1 and forming temperatures of ST-78°C, ST-22°C and ST+30°C. The analysis of these experiments provided the necessary data for the parameter derivation for the microstructure model. The activation energy necessary for the Zener-Holomon parameter Z, as well the of Z dependent strain hardening exponent as well as the kinetics of recrystallization could be determined. Typical semi empiric models have been used to describe the grain structure evolution as a function of recrystallization and grain growth [2]. Derivation of the parameters of the Johnson-Mehl-Avrami-Kolomogorow model [3,4,5] showed that recrystallization in René 65 is mainly meta-dynamic. The obtained parameters can be integrated into a Fortran user routine and implemented in the finite element software DEFORM 2D™ in order to predict microstructural changes during and after thermomechanical processing.