Science diplomacy creates possibilities for trust building in international relations. We draw on studies of science, diplomacy, and trust in IR and explore Chinese scientific activities in the Arctic in order to sketch out four mechanisms that produce procedural and generalized forms of trust: the sharing of resources and infrastructure, personal interactions, science‐based institutions, and spillover effects. The materials of the case of ‘science China’ also help to question assumptions about science diplomacy in IR as they illustrate its inherent tensions, boundaries, and limitations.