Abstract: A cooling arrangement for electronic components mounted in racking systems in which access to the components is gained by moving a rack with reference to its supporting structure comprises a thin-walled cooling chamber of shallow depth carried by a fixed structure and arranged to be urged against and to conform with a wall of the rack, a pressurized liquid coolant being passed through the cooling chamber in the form of a lamina flow sheet to provide efficient cooling, the chamber being urged into its conformal position by an expandable chamber which is itself expanded by the pressurized coolant. Coolant is firstly used to expand the expandable chamber and then is ducted from that chamber into the cooling chamber from which it exits for subsequent recycling.