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This article presents a life-cycle sustainability assessment of electricity generation systems in Portugal, namely coal, natural gas, hydro (large and small), wind, and photovoltaic systems, and evaluates their environmental and socioeconomic impacts. The environmental life-cycle assessment methodology was used to quantify impacts in metal depletion, fossil fuel depletion, global warming, ozone depletion, terrestrial acidification, freshwater eutrophication, aquatic acidification, water scarcity footprint, and toxicity (towards freshwater ecosystems and humans). Socioeconomic impacts were estimated for employment provision, dependence on fossil fuels, capacity factor, and levelised cost of electricity. The results show that electricity based on coal has the highest environmental impacts in all categories except: metal depletion (wind had the highest impacts), ozone depletion (natural gas), water scarcity footprint (large hydro), and freshwater ecotoxicity and human toxicity, non-cancer (photovoltaic). For socioeconomic categories, there was a greater variability. Photovoltaic generated the most employment and wind-based generation was estimated to have the lowest levelised cost, while coal generated the second-highest total employment and the third-lowest levelised cost. Overall, the life-cycle sustainability assessment shows small hydro as the most environmentally and socioeconomically sustainable system. By exposing the trade-offs amongst technologies and sustainability dimensions, this work provides an informed basis for future energy policy in Portugal. (C) 2019 Elsevier Ltd. All rights reserved.