This study conducted a Life Cycle Assessment (LCA) of alternative (electric and hydrogen) and conventional diesel buses in a large metropolitan area. The primary focus was on hydrogen derived from coke oven gas, a byproduct of the coking process, which is a crucial step in the steel production value chain. The functional unit was 1,000,000 km traveled over 15 years. LCA analysis using SimaPro v9.3 revealed significant environmental differences between the bus types. Hydrogen buses outperformed electric buses in all 11 environmental impact categories and in 5 of 11 categories compared to conventional diesel buses. The most substantial improvements for hydrogen buses were observed in ozone depletion (8.6% of diesel buses) and global warming (29.9% of diesel buses). As a bridge to a future dominated by green hydrogen, employing grey hydrogen from coke oven gas in buses provides a practical way to decrease environmental harm in regions abundant with this resource. This interim solution can significantly contribute to climate policy goals.