Hong Kong currently does not have a long-term decarbonization strategy or target beyond 2030 in place. It is critical for Hong Kong to formulate a long-term decarbonization plan to which the short- and medium-term actions could conform. WRI and Civic Exchange collaborated with Energy Innovation LLC to develop the Hong Kong Energy Policy Simulator (EPS), an online scenario analysis tool, which aims to provide technical support for developing Hong Kong’s 2050 deep decarbonization strategy. This technical note describes the structure, input data sources, outputs, limitations, and future development, as well as the online interface, of the Hong Kong EPS. The.