Abstract This paper compares the sustainability of pressurized alkaline water electrolysis systems operating at different places in Europe (Austria, Germany and Spain). Using a Life Cycle Sustainability Assessment (LCSA) approach, an advanced electrolysis system (6 MW) based on Zirfon membranes is investigated. Results of Life Cycle Assessment, Life Cycle Costing and social Life Cycle Assessment plus subsequent normalizing, weighting, and aggregation in LCSA are assessed. A closer look reveals that the choice of weighting concept has a crucial impact on results. As main outcome, the comparison illustrates that hydrogen production via electrolysis in Germany performs best if weak sustainability (equal weighting of dimensions) is assessed. Using the strong sustainability concept (considering only environmental results) Germany yields worst results mostly due to the environmental impacts of its electricity generation.