The disclosure relates to a connection device, in particular a heavy-duty plug-type connection, with a first connector and a second connector, which each have a contact-making element in order to produce an electrical connection in the connected state of the connectors; the connectors bearing against one another at a connection region in the connected state; at least one of the connectors comprising a coolant line with one or more access points for the supply and discharge, respectively, of a coolant; the coolant line being provided at the contact-making element in order to dissipate heat from a contact point between the contact-making elements; all of the access points of the coolant line being arranged outside of the connection region.