OMV is on its way to establish itself as one of Europeans major energy supplier. Therefore, the company is interested in green energy technology and likes to invest in that field of energy production in the future. OMV has already done research on geothermal energy technology and carried out one geothermal energy project in Austria. To be able and ready to increase their geothermal energy portfolio in the next few years, OMV was interested in developing an as-sessment tool for the geothermal energy potential of their E&P country portfolio. In a first step, a research on all countries from the OMV E&P portfolio was done and based on the facts the countries were described shortly by their political, economic and geological aspects. As the OMV E&P portfolio consists of 17 countries which all have different geothermal energy potentials, it was decided to run a pre-screening upfront to filter out all countries with an economical meaningful geothermal energy production potential, to be able to achieve better results regarding the sensitivity of the needed data-packages. By conducting this step, the countries could be minimized to nine potential countries. To establish the desired assessment tool, a system has been defined as framework for all further steps. However, multiple criteria decision analysis with a SWING weighting method was chosen. After the system evaluation step, all criteria with an influence on a geothermal energy production projects were defined. This process was accomplished with the aid of a top-down approach, a political-economic-social-technological-analysis and expert interviews. After the assessment tool was established, experts weighted all criteria on their importance for the overall system, the criteria were assigned their appropriate key figure and the different countries were evaluated. To assess the plausibility of the results a sensitivity analysis was carried out. An easy and understandable assessment tool to determine the geothermal energy potential of different countries was developed, and was proved on its functionality. The results of the tool show reasonable values, with Romania having the highest potential, as the two most interesting regions are based there.