The Management of polymer processing companies has to make strategic decisions about their product developments and those decisions need to be fast and accurate in the 21th century. Only on this basis, a keeping up of a relative competitive advantage towards other companies can be ensured. It is a challenge for the decision maker because it is not possible to see all the consequences of the decision in the future and our systems have also some blind regions. Therefore, this scientific investigation helps developing a decision solver, which paves the management towards a rational and explicit decision making The focus of this thesis will be on the analysis of different decision theories. The thesis deals with the question how decisions are made in general. In the first part of the thesis, which is defined as theory part, decision making techniques are investigated and compared to each other. In the second part, which is defined as practical part, the focus is on gathering information about decision making in polymer processing companies. This is done by expert interviews. The information collected from all experts in combination with the theory, built the basis for the decision solver. The programming language Visual Basics for Applications is used for creating the framework for the solver. The core element is represented by a decision matrix. This matrix consists out of criteria and options for the decision setup. The result of the decision matrix is a weighting of the options with points. On the basis of these results, it is possible to make a strategic decision about the polymer product. Additionally, decision principles are derived from the collected information. The thesis ends by presenting three particular applications of the decision solver in the field of poly-mer engineering: Application of the solver in the Stage-Gate process in injection moulding, application of the decision solver in the Quality by Design in the Hot-Melt extrusion and application of the decision solver in the Quality by Design of injection moulding simulations. These examples demonstrate the broad application field of the decision solver. After setting up the solver, this will be implemented in the departments of the project partners, in order to supervise decision processes in a rational way.