This paper introduces the basic concepts of hydro-hegemony which are employed in the analysis of the contributors of this special issue. It emphasises the roles of hegemony, power and political–economy processes in shaping international transboundary water relations. Central to the analysis is Lukes’ concept of the three dimensions of power and Gramscian notions of hegemony (see S. Lukes, Power: A Radical View, 2005). Hegemony depends on the skilful use of hard and soft forms of power, between formally equal parties such as nation states. Hydro-hegemony is hegemony active in international transboundary water settings, the analytical framework for which is laid out in detail by Zeitoun and Warner in Water Policy vol 8 (2006, 435–460). The challenges of conceptualising the complex nexus of international water relations are also addressed. A recurring theme is that both power and political economy processes are especially effective when they operate invisibly. The approach furthermore sets the frame for exploration of improvement of the options of hegemon riparians and non-hegemon riparians alike for more principled transboundary water governance.