Purpose This paper aims to study the effects of knowledge acquisition on innovation performance and the moderating effects of human resource management (HRM), in terms of employee retention and HRM practices, on the above-mentioned relationship. Design/methodology/approach A sample of 129 firms operating in a wide array of sectors has been used to gather data through a standardized questionnaire for testing the hypotheses through ordinary least squares (OLS) regression models. Findings The results indicate that knowledge acquisition positively affects innovation performance and that HRM moderates the relationship between knowledge acquisition and innovation performance. Originality/value With the increasing proclivity towards engaging in open innovation, firms are likely to face some tensions and opportunities leading to a shift in the management of human resources. This starts from the assumption that the knowledge base of the firm resides in the people who work for the firm and that some HRM factors can influence innovation within firms. Despite this, there is a lack of research investigating the link between knowledge acquisition, HRM and innovation performance under the open innovation lens. This paper intends to fill this gap and nurture future research by assessing whether knowledge acquisition influences innovation performance and whether HRM moderates such a relationship.