<p>This study examines the relationship between intellectual capital and open innovation in small and medium-sized enterprises (SMEs) in Argentina, focusing on human, structural, and relational capital. It analyzes whether human capital contributes to the development of open innovation in SMEs and whether this effect is mediated by structural and relational capital. A quantitative study was conducted with 259 manufacturing SMEs in Argentina, using data collected through a structured questionnaire administered to managers. The validity of the constructs and the theoretical model was assessed through structural equation modeling. The findings indicate that human capital significantly influences open innovation; however, this effect is fully mediated by both structural and relational capital. Structural capital mediates the relationship by supporting organizational coordination, cooperation, and knowledge exchange, while relational capital enables firms to identify market opportunities, acquire external knowledge, and enhance innovation capabilities. The study highlights the importance of intellectual capital in strengthening open innovation and offers insights for SMEs and policymakers. It contributes to the literature by expanding empirical evidence on intellectual capital and open innovation in SMEs, particularly in emerging economies such as Argentina, where evolving business conditions underscore the need to develop and leverage intellectual capital.</p>