The first part of this project is the study, mapping and reengineering of business processes in the operation of Grecotel S.A. hotels, as well as the identification of the changes that will be needed in the framework of an ERP (SAP R/3) system implementation. An analytical hierarchical methodology is used for the process reengineering and economic indexes are proposed in order to monitor the efficiency of various procedures in the hotel operations management. In the second part of the project a number of decision support tools are developed and used in order to help the management of the company in the decision making process. These tools aim at their integration with the ERP system in order to use the information extracted from it to give reliable solutions. In detail: A Cost-Volume Profit Analysis (structured in an electronic platform) is proposed to evaluate the efficiency of different hotel in business units. A Simulation set-up is introduced to the company to monitor the effectiveness of the font desk operation in a hotel. The Analytical Hierarchical Process is used to provide the optimal choice in multi-criteria decision making problems, such as the selection of the most suitable vendor. The concept of Economic Order Quantity is examined in the inventory control in contrast to empirical methods. Finally, a Linear Programming Optimisation model is developed to enhance the decision-making process concerning new investments (defining the optimal product mix of different room types in a new hotel).