Attracting and retaining committed teachers who are willing to perform extra-role activities that go above and beyond their prescribed jobs can be a key asset to an academic institution. Turnover intentions and organisational citizenship behaviours are important considerations for managers of organisations, including universities. The main aim of this study was to investigate a model of organisational citizenship behaviour that included turnover intention as a mediator variable, five predictor variables of distributive justice, procedural justice, affective commitment, continuance commitment and perceived organisational support (POS), and organisational citizenship behaviour directed at organisations (OCBO). A questionnaire was completed by 107 academic participants from five schools at the University of Papua New Guinea. Distributive justice, procedural justice, affective commitment, continuance commitment and POS were significant predictors of turnover intention but not OCBO. However, turnover intention did not mediate the relationships between the predictors and OCBO. The nonsignificant results were mainly due to the participants’ high ratings of 6 or 7 on the 7-point OCBO scale, which inflated the overall score. This may have been affected by several factors such as the participants’ social desirability response, which is common in self-reports. It could also denote that the employees’ performed higher levels of OCBOs despite their intention to leave the university. Supplementary analyses showed age, gender and organisational tenure were correlates of turnover intention. The major implications from this research are that managers of universities need to foster organisational justice, organisational commitment and organisational support to reduce turnover intentions and to enhance OCBOs.