Purpose - The purpose of this paper is to examine why and when employees hide knowledge. Individuals may tend to hide knowledge when they have strong psychological ownership feelings over knowledge. Therefore, this research builds and tests a theoretical model linking knowledge-based psychological ownership with knowledge hiding via territoriality.Design methodology approach - Data were collected from knowledge workers in China via a three-wave web-based survey. The final sample was 190 cases. Hierarchical regression models and a bootstrapping approach were used to test the hypotheses.Findings - The results show that knowledge-based psychological ownership positively affects knowledge hiding. Territoriality fully mediates the link between knowledge-based psychological ownership and knowledge hiding. Moreover, organization-based psychological ownership moderates the positive link between territoriality and knowledge hiding. Specifically, territoriality will mediate the indirect effect of knowledge-based psychological ownership on knowledge hiding when organization-based psychological ownership is low, but not when it is high.Research limitations implications - The research reflects that to reduce knowledge hiding, organizations should focus on practices that can decrease employees' self-perception of possession of knowledge and territoriality and that can strengthen employees' psychological ownership for organizations.Originality value - Although many actions have been adopted to foster knowledge management in companies, knowledge hiding is still prevalent in work settings. This paper highlights the predictive power of knowledge-based psychological ownership on knowledge hiding, and the mediating role of territoriality in the link between knowledge-based psychological ownership and knowledge hiding.