Purpose: The purpose of this paper is to empirically examine the fundamental process through which transformational leaders play a significant role in employees' knowledge sharing by investigating mediating roles of individual affects, particularly psychological empowerment, organizational commitment and organizational citizenship behavior (OCB). Design/methodology/approach: Structural equation modeling, including confirmatory factor and path analysis, is conducted to test proposed hypothesis. Findings: The results of this study indicate significant direct effects of transformational leadership on psychological empowerment, organizational commitment and OCB. Moreover, transformational leadership also shows an indirect effect on employees' OCB, which, in turn, is identified as the primary factor that influences knowledge sharing. However, organizational commitment does not provide a significant influence on knowledge sharing. These findings highlight the importance of mediating roles, particularly OCB, to predict employees' knowledge-sharing intention. Originality/value: Identifying structural determinants of knowledge sharing is an important scholarly agenda. In particular, the mechanisms and processes by which leadership exerts influence to motivate employees to share knowledge deserve scholarly inquiry, and there, is a need for more research to understand the mechanisms and processes through which leadership influences individual motivation and attitudes toward pro-social behaviors, such as knowledge sharing.