The process of developing a research proposal is challenging for many postgraduates, especially with the restricted time for supervision and the dominance of supervisory unidirectional written feedback on postgraduates' academic texts that leave almost no or limited space for students to negotiate and clarify their work with supervisors. Therefore, the current study focused on the opportunities and challenges afforded by peer feedback practices to 15 postgraduates in research proposal development in a Malaysian public university. The qualitative analysis of the observation, video recorded face-to-face (FTF) and online peer feedback and follow-up interviews showed that peer feedback assists postgraduates to identify issues related to focus and titles, formulation of research problem, objectives and questions, research contribution and significance, theory and literature review, methodology and alignment in research proposals. Peer feedback is also a vehicle for creating interactions and meaning negotiations. Although most of the postgraduates valued peer feedback, feedback practices are challenged by students' initial lack of active participation in peer feedback, the issue of reliability of peers' ideas and suggestions and hesitance and worries about sharing their work online. The study offers useful pedagogical implications for supervisors and researchers in maximising the value and uptake of peer feedback for postgraduates in their research work.