Introduction: The economy of Vietnam, a highly populated tropical country with a per capita gross domestic product of $ 8 000, is growing rapidly, but there are few recent studies of general scope about its scientific productivity and how it compares with other tropical countries. Objective: To identify trends in Vietnamese science and compare them with trends in other tropical countries. Methods: We extracted data about scientific papers, in all disciplines that had Vietnam as country in the Science Citation Index Expanded for the period 1991 to 2018, focusing on type of publication, language, subject, authorship, collaboration, , and citations. Results: Vietnam publishes more document types than other tropical countries, and those in this particular database are mostly in English, albeit most Vietnamese science is published in Vietnamese and not covered by the index. The primary categories were multidisciplinary materials science, mathematics, and applied mathematics. Most collaboration was done with the USA, Japan, South Korea, and France. A large number of articles were published by the Vietnam Academy of Science and Technology, and the most frequent foreign collaboration was with University of Oxford. Conclusion: the tropical countries of Latin America, Africa, and Asia studied in our project have some similarities but also crucial differences. Science is developing rapidly in Vietnam and the production of articles in Vietnamese, which represent the vast majority of research in the country but is not included in this database, should also be studied.

Keywords: scientific productivity, scientific collaboration, Asia region, tropical science