Purpose: This article explores the roles and the expertise of Hong Kong in the internationalization of public administration education.Design/methodology/approach: The methodology is based on the data of 5 internationalization initiatives of one Hong Kong university with its internationalization partners in Macau, Korea, Australia, Russia and Finland. The data obtained lasted for a period of 18 months, from September 2019 to March 2021.Findings: The finding of this study revealed that (1) there are 5 “pubtropolis roles” (roles of a public administration metropolis) of Hong Kong in the internationalization of public administration education in China, Asia, Asia-Pacific, Belt-and-Road and Europe. The findings also revealed that (2) Hong Kong served as a pubtropolis with its “5C” expertise in curriculum innovation, customized training, competence framework, competence assessment and comparative policy.Research limitations/implications: As the methodology of this article is based on the data of 5 internationalization initiatives of one Hong Kong university by one academia only, further studies can be conducted at department, faculty or university level for multiple academia.Practical implications: There are two practical implications: (1) The more the roles of a city, the broader the view in its internationalization of public administration initiatives; (2) Hong Kong could further tap on its expertise in “5C” in public administration: curriculum innovation, customized training, competence framework, competence assessment and comparative policy to exert its “geo-management” power.Social implications: This article argues that public services can be improved by the setting up of “Sabbatical Leave Scheme for Internationalization of Public Administration” by respective governments to sustain the impacts observed.Originality/valueIt is from the author's original work. Copyright © 2022 Emerald Group Publishing Limited.