Hydrogen fi-om decentralized water electrolysis is one of the main fuelling options considered for future fuel cell vehicles. In this thesis, a model is developed to determine the key technical and economic parameters influencing the competitive position of decentralized electrolyhc hydrogen. This model, which incorporates the capital and energy costs of water electrolysis, as well as a monetary valuation of the associated greenhouse gas (GHG) emissions, is used to analyze the competitive position of electrolytic hydrogen in three specific locations with distinct electricity mix:​ Vancouver, Los Angeles and Paris. Using local electricity prices and fuel taxes, electrolytic hydrogen is found to be commercially viable in Vancouver and Paris. Hydrogen storage comes out as the most important technical issue. But more than any techcal issue, electricity prices and fuel taxes emerge as the two dominant issues affecting the competitive position of electrolytic hydrogen. The monetary valuation of GHG emissions, based on a price of $20/ton of CO₂, is found to be generally insufficient to tilt the balance in favor of electrolytic hydrogen.