A jet impingement cooling apparatus comprising: a fluid channelling structure configured to engage against a target surface and thereby define a flow volume through which a fluid can flow, the fluid channelling structure comprising: a plurality of inlets , each inlet opening into the flow volume and configured to allow a fluid to be jetted directly onto the target surface from the inlet and into the flow volume ; a plurality of outlets , each outlet opening into the flow volume and configured to allow the fluid to be removed from the flow volume through the outlet ; and a plurality of flow directing features together forming a plurality of channels fluidly connecting the inlets and the outlets , wherein the flow directing features are arranged such that there is no straight path through the flow volume from a region of the flow volume facing any one of the inlets to a region of the flow volume facing any one of the outlets , wherein: the flow directing features are configured such that, in use, a time averaged flow direction of fluid in contact with a surface of each flow directing feature is more nearly perpendicular to a direction of jetting of the fluid from a nearest inlet than parallel to said direction of jetting, for at least a majority of the surface of the flow directing feature ; characterized in that one or more pairs of the inlets and outlets are configured such that a majority of fluid jetted onto the target surface from the inlet of the pair will be removed from the flow volume through the outlet of the same pair. a plurality of inlets , each inlet opening into the flow volume and configured to allow a fluid to be jetted directly onto the target surface from the inlet and into the flow volume ; a plurality of outlets , each outlet opening into the flow volume and configured to allow the fluid to be removed from the flow volume through the outlet ; and a plurality of flow directing features together forming a plurality of channels fluidly connecting the inlets and the outlets , wherein the flow directing features are arranged such that there is no straight path through the flow volume from a region of the flow volume facing any one of the inlets to a region of the flow volume facing any one of the outlets , wherein: the flow directing features are configured such that, in use, a time averaged flow direction of fluid in contact with a surface of each flow directing feature is more nearly perpendicular to a direction of jetting of the fluid from a nearest inlet than parallel to said direction of jetting, for at least a majority of the surface of the flow directing feature ; characterized in that one or more pairs of the inlets and outlets are configured such that a majority of fluid jetted onto the target surface from the inlet of the pair will be removed from the flow volume through the outlet of the same pair. the flow directing features are configured such that, in use, a time averaged flow direction of fluid in contact with a surface of each flow directing feature is more nearly perpendicular to a direction of jetting of the fluid from a nearest inlet than parallel to said direction of jetting, for at least a majority of the surface of the flow directing feature ; characterized in that one or more pairs of the inlets and outlets are configured such that a majority of fluid jetted onto the target surface from the inlet of the pair will be removed from the flow volume through the outlet of the same pair. <EOS>