The qualifications of faculty members play a crucial role in the success of educational systems. Academics with a high level of organizational citizenship behaviour (OCB) are mostly valued due to the excellent services they offer to their students. This study aims to investigate the impact of faculty members' personality traits on their OCB. Additionally, it examines the moderating role of the perceived university brand in the relation between the two variables. This study is quantitative in nature and the sample includes professors working at seven prestigious Iranian universities. Overall, 422 questionnaires were gathered. By the use of Smart-PLS, the results indicate that academic members with "conscientious," "agreeable" and "openness" personality traits tend to show higher levels of OCB. On the flip side, "neuroticism" negatively predicts academics' OCB. Moreover, this research indicates that "perceived university brand" significantly moderates only the effect of "openness" trait on faculty members' OCB, meaning that professors with "openness to experience" traits who are working at such universities, are more likely to engage in OCB.