The rapidly advancing digitization in companies and purchasing departments is an ongoing trend that is undisputed by experts from the industry and scientific researchers. However, it seems that adoption of these concepts is not progressing very fast. Many companies fear high investment costs and are overwhelmed by the amount of information available on the greater topic of industry 4.0 and therefore prefer to wait and observe. The little amount of tools and instruments available to realize approaches towards purchasing 4.0 and digitization also disencourages companies who are not digital pioneers. The aim of this master's thesis is to help close that gap by providing a maturity model for purchasing 4.0 as well as compiled information on purchasing 4.0 and digitization in purchasing, based on an extensive literature review. To test the maturity model, it has been applied to an exemplary company. With information accumulated by expert interviews, the purchasing 4.0 maturity of the company pewag has been determined and suggestions to guide the purchasing department successfully towards a digital future have been derived.