In this thesis we analysed environmental impacts of producing 1 kg of hydrogen. We did it using life cycle assessment. We used GaBi software for evaluating environmental impacts. With usage of environmental indicators from methodology Environmental Footprint – EF 3.0 we defined which hydrogen production technologies have the biggest and which the smallest impact on the environment. The cleanest hydrogen is the one produced as a by-product from chlor-alkali production. Hydrogen produced with cracking and steam reforming of natural gas follows. The biggest impact on the environment has electrolysis of water, in which the input electric energy is produced mainly from nuclear, hydro and thermal power plants.