Spending on investments in integrative information systems (IIS) has considerably risen during the last few years due to a high need for linking various information systems. The demand for integrating the systems stems from developments like mergers and acquisitions and is typically satisfied in practice using Enterprise Application Integration solutions, Enterprise Resource Planning systems, Portals, or Data Warehouses. For the valuation of such an investment previous literature recommends the use of a real options analysis (ROA) since traditional capital budgeting methods such as the Net Present Value underestimate its value. Contrary, the ROA is able to conveniently account for managerial flexibility, represented by the possibility to implement follow-on opportunities, generated by the IIS. However, in practice ROA suffers from a lack of appliance mainly because of its complexity. This thesis precisely closes this gap and develops a simplified process model for a ROA by exactly tailoring the broad real options concept to the requirements of an investment valuation of IIS. For that, it reviews option pricing models from the financial world as well as previous research in the area of ROA and creates the desired model by conducting a ROA for four case studies in detail. The study reveals new findings concerning the question of how a decision-maker can apply the real options method and at the same time, when he/she is able to abandon a detailed ROA or a ROA at all. (author's abstract)