Hong Kong is on the cusp of becoming the world's first city powered entirely by hydrogen energy, signaling a monumental shift towards green city development. HK Electric has spearheaded the integration of hydrogen into energy sources, with construction at Lamma Power Station set to boost decarbonization efforts. Collaborating with Mitsubishi at Takasago Hydrogen Park, Hong Kong is at the forefront of hydrogen energy development globally. Government support for hydrogen trials across various sectors, including electricity production and transportation, further propels the city's hydrogen initiative. Pilot trials have demonstrated hydrogen's efficiency, cleanliness, and versatility, paving the way for significant carbon emission reductions by 2035. The city's proactive approach to hydrogen energy not only showcases technological advancements but also sets a global example for cities transitioning to sustainable energy sources. With a vision to operate solely on hydrogen, Hong Kong's hydrogen revolution may serve as a blueprint for other cities in the global energy transition, making it a beacon of hope for a sustainable future.