Purpose: The purpose of this paper is to deal with the topic internationalization of higher education institutions (IHEI), in terms of the research they engage in. The main motivation for the study is to understand the role of researchers in the internationalization of the institutions in which they work through the academic activities they perform. Based on the assumption that each of the researcher's internationalization activities leads, to some extent, to a greater internationalization of HEI in which it operates, the following question was proposed: Do researchers' personal characteristics and academic activities affect the internationalization of their (higher education) institutions? Design/methodology/approach: This qualitative study adopted as main methods a review of the literature on internationalization of higher education and in-depth interviews based on a semi-structured script with an intentional sample. A sample of 16 researchers was selected for interview using the snowball technique of sample selection. Findings: The paper provides theoretical and empirical insights into the characteristics of researchers that influence the internationalization of HEIs. These include the researchers' international academic experience; insertion in international collaboration networks; international co-authorship; and experience in international publications. These are the four main factors that emerge at the individual level (researcher) that positively impact IHEI. Originality/value: The paper responds to a gap found in the literature on the underestimated role of researchers in the internationalization process of HEIs in which they work.