Hydrogen is seen as a clean energy carrier that will aid in phasing out fossil fuels, and liquid hydrogen will likely play a role in the global hydrogen economy. However, Life Cycle Assessment researchers and process engineers widely report having insufficient means to accurately assess the environmental impacts of hydrogen liquefaction. This thesis presents an LCA study of hydrogen liquefiers based on current public data and literature. Additionally, a simplified model for hydrogen liquefaction was developed to aid future LCA researchers. An original Life Cycle Assessment of hydrogen value chains incorporating liquefaction is also included. The environmental harm was calculated in the form of direct monetary prevention costs, using the increasingly popular Eco-cost method. The environmental impacts of various sizes and types of hydrogen liquefiers are compared, while hotspots of environmental harm were determined. The main findings indicate that the primary source of environmental impact for hydrogen liquefaction is power consumption, with refrigerant leakage being insignificant as long as hydrocarbons are used for the precooling mixture.