This study examines the impact of CEO characteristics on firm performance focusing on R&D investment in Korea. Specifically, we examine the effect of CEO characteristics on R&D investment and the moderating role of CEO characteristics in the relationship between R&D investment and firm performance. Among various CEO characteristics, education-related variables and age are significantly associated with R&D investment. Moreover, we find that only newly appointed CEOs or CEOs who have majored in sciences and engineering tend to invest in R&D efficiently, seemingly to boost firm performance. Based on the results, this study provides better understanding of the relationship between R&D investment and firm performance, highlighting CEO characteristics as a moderator that could be interpreted as R&D efficiency.