Numerous cities aim to mitigate their contribution to climate change and provide a liveable environment in the context of sustainable development. In order to measure these efforts, benchmarking performance would be a good solution. Methods for environmental analysis have their limitations when it comes to evaluating a city and other aggregated indicators focus on certain aspects of a sustainable or liveable settlement. The SDEWES Index was used for benchmarking several cities of different sizes in terms of metrics related to energy, water and environmental systems successfully thus it was chosen to compare the performance of Veszprém and Zalaegerszeg, two environmentally conscious Hungarian county seats of roughly the same size and population. The SDEWES Index consists of 7 dimensions, namely energy consumption, industrial profile with CO2 emissions, CO2-saving measures, R&D, renewable energy potential and utilization, water and environmental quality, and social environment and sustainability policy. Each dimension is composed of 5 indicators that provide information on sustainable development of energy, water and environmental systems in cities. Using the SDEWES Index the strengths and weaknesses of the two cities are highlighted, locating those key parameters where improvement can be achieved. Both for Veszprém and Zalaegerszeg progress could be realized concerning energy-saving measures and the proportion of green areas could be increased. To improve the method and facilitate a more comprehensive comparison of cities of differing sizes, data should be provided concerning the territory or population. Also, the definition and inclusion of a worst and best case scenario that takes into account the parameters would be advantageous in terms of a comparison. These were named ‘horror’ and SDEWES cities by the authors, respectively.