Abstract: A method of cleaning cavities on gas turbine components, in particular on gas turbine blades, wherein a caustic cleaning medium and subsequently a rinsing medium are directed for this purpose in particular repeatedly through the or each cavity, to be cleaned, of a gas turbine component is disclosed. Before the treatment of the or each cavity with cleaning medium and rinsing medium, the or each cavity of the gas turbine component is flooded with inert gas. The gas turbine component, with the inert gas atmosphere in the or each cavity being maintained, is then subjected to a preferably repetitive thermal treatment, wherein the component is heated for this purpose in a first time interval, is held at this temperature for a second time interval and is then cooled in a third time interval. The cleaning medium and the rinsing medium are then directed through the or each cavity.