Hydrogen fuel cell electric vehicles (FCEVs) convert hydrogen and oxygen into electricity through electrochemical reactions, emitting only water vapor while offering rapid refueling (3-5 minutes) and extended ranges (500-700 kilometers). Proton exchange membrane (PEM) fuel cells dominate vehicular applications, operating at 60- 80% with power densities reaching 3-4 kW/L. Fuel cell stacks contain multiple cells (300-400) arranged in series, with hydrogen supplied from on-board storage tanks pressurized to 350-700 bar using carbon fiber composite materials. The electrochemical process produces electricity with efficiencies of 40-60%, superior to internal combustion engines, while waste heat supports cabin heating. Hydrogen production pathways include steam methane reforming (currently dominant but producing CO2), electrolysis using renewable electricity (green hydrogen), and emerging technologies like methane pyrolysis producing solid carbon. Hydrogen refueling infrastructure remains limited, with approximately 1000 stations globally, compared to hundreds of thousands of gasoline stations - the primary barrier to widespread FCEV adoption. Station costs range from 1- 2 million dollars per 200 kg/day capacity, with hydrogen delivery via trailers, pipeline, or on-site production. Storage challenges include hydrogen's low volumetric energy density requiring high-pressure systems or cryogenic liquefaction, and material embrittlement issues in steel infrastructure. FCEVs excel in heavy-duty applications (trucks, buses, trains) where battery weight penalties and long-distance operation favor hydrogen's energy density advantages.