This paper reviews recent Life Cycle Assessment (LCA) studies of various hydrogen production pathways, aiming to identify the most environmentally sustainable methods. Steam methane reforming (SMR) is used as a benchmark with an average Global Warming Potential (GWP) of 11 kgCO2eq/kgH2. Hydrogen produced from water electrolysis powered by renewable energy (green H2) or nuclear energy (pink H2) shows the lowest impacts, with mean values of 2.02 kgCO2eq/kgH2 and 0.41 kgCO2eq/kgH2, respectively. Grid electricity-powered electrolysis (yellow H2) increases the carbon footprint to 17.2 kgCO2eq/kgH2, with peaks at 41.4 kgCO2eq/kgH2 for countries with low renewable energy production. Waste pyrolysis and gasification have three times higher emissions than SMR, while using residual biomass and biowaste significantly reduces greenhouse gas emissions. The acidification potential is similar across technologies except for biomass gasification, which has higher and more scattered values. Abiotic Depletion Potential (ADP) is hindered by the lack of established recycling strategies for electrolysis technologies. The study also identifies hotspots for each hydrogen production process to highlight areas with the highest environmental burdens. The results provide a comprehensive overview of the environmental impacts of different hydrogen production methods, emphasizing the importance of renewable energy sources and the need for better recycling strategies.This paper reviews recent Life Cycle Assessment (LCA) studies of various hydrogen production pathways, aiming to identify the most environmentally sustainable methods. Steam methane reforming (SMR) is used as a benchmark with an average Global Warming Potential (GWP) of 11 kgCO2eq/kgH2. Hydrogen produced from water electrolysis powered by renewable energy (green H2) or nuclear energy (pink H2) shows the lowest impacts, with mean values of 2.02 kgCO2eq/kgH2 and 0.41 kgCO2eq/kgH2, respectively. Grid electricity-powered electrolysis (yellow H2) increases the carbon footprint to 17.2 kgCO2eq/kgH2, with peaks at 41.4 kgCO2eq/kgH2 for countries with low renewable energy production. Waste pyrolysis and gasification have three times higher emissions than SMR, while using residual biomass and biowaste significantly reduces greenhouse gas emissions. The acidification potential is similar across technologies except for biomass gasification, which has higher and more scattered values. Abiotic Depletion Potential (ADP) is hindered by the lack of established recycling strategies for electrolysis technologies. The study also identifies hotspots for each hydrogen production process to highlight areas with the highest environmental burdens. The results provide a comprehensive overview of the environmental impacts of different hydrogen production methods, emphasizing the importance of renewable energy sources and the need for better recycling strategies.