This article describes the internationalization of the Scientific Electronic Library Online (SciELO), an open-science programme aimed at the development of capacities and infrastructure in research communication. It manages open-access collections of preprints, articles, research data, books, and book chapters, with a focus on national collections of non-profit peer-reviewed journals published by research communities of academic institutions, scientific societies, and associations. Celebrating 25 years of regular operation, SciELO improves research communication through professionalization, internationalization and sustainability of the indexed journals, maximizing their visibility and impact. In Brazil, the internationalization efforts by SciELO are aligned with national research policies, especially the internationalization of graduate programmes. The SciELO Brazil collection of journals evolves by adopting English solely or with Portuguese to improve the contribution of multilingualism to performing research by subject field. This article covers two decades of scientific literature in SciELO Brazil from 2003 to 2022. During this time, articles written in English or simultaneously in Portuguese and English increased significantly, resulting in a corresponding rise in access and citations received. The progress of the internationalization of the journals in the SciELO Brazil collection through multilingualism has been challenging both operationally and programmatically.