Purpose: This study aims to examine reciprocal exchanges in knowledge networks using temporal differentiation of knowledge exchanges. To date, research on horizontal knowledge networks rather overlooks the temporal perspective, which could explain the dynamics of exchange in those networks. Design/methodology/approach: The paper reports on a study of four horizontal knowledge networks in the UK over a period of 18 months. Findings: The findings integrate three temporal dimensions of timescale, timeliness and time modalities. The dimensions have implications for the way knowledge is exchanged (or not), which can in turn sustain or stymie productive knowledge exchange in horizontal knowledge networks. Research limitations/implications: The study encourages researchers to attend to the micro-processes of knowledge exchanges through the integrative framework of temporalities. While this study examined horizontal networks, future research can be extended to analysing temporalities in other types of networks. Practical implications: It seeks to inspire practitioners to appreciate how the impacts of knowledge networks play out in/over time, and how more effective coopetitive knowledge-sharing environments can be created and sustained by taking differentiated time structures into account. Originality/value: This study contributes to the knowledge management literature by providing a temporal perspective to understand reciprocal knowledge exchanges in horizontal knowledge networks.