In the project business, about 50 to 60% of the costs can be attributed to the purchase of components and services. The purchase or the result of the supplier selection for the project can result in positive as well as negative deviations from the project's objectives as a consequence of the process flow. The selection of the supplier must therefore be done with great care. The aim of this thesis is to develop a supplier evaluation tool with which the risk of the supplier to the project can be assessed before awarding the contract. The concept of the supplier evaluation tool is to offer a possibility to support the supplier selection and to guarantee the transparency of the selection, especially afterwards. The basis of the supplier evaluation tool is a maturity model. The maturity model is based on the dimensions "quality", "costs", "time" and "sustainability". These four dimensions can be used to guide supplier selection decisions by the supply chain management. The developed model defines four criteria for each dimension, which determine the maturity level of the supplier in terms of its project maturity via a point evaluation. The supplier evaluation tool, with the project supplier maturity model, offers in its structure a basis for communication between the procurement and the project management as well as a joint decision-making basis of the project management together with the supply chain management and is used for the later traceability of the supplier selection. The supplier evaluation tool was developed in cooperation with a global concern with its head office in Styria. As a supplier of plants, systems, equipment and services for various industries, the group is a technology and market leader in its business sector. The majority of its business activities are concerned with project business, project planning and the construction of plants, designed directly for the customer. In this function, it has the tasks and responsibilities for planning the plant, purchasing the necessary components and services, manufacturing and quality assurance of the customer-specific components, delivery, installation and commissioning.