Abstract: A variable geometry turbine comprise a housing; a turbine wheel supported in the housing for rotation about a turbine axis; and an annular inlet passage upstream of said turbine wheel defined between respective inlet surfaces defined by an annular nozzle ring and a facing annular shroud. The nozzle ring and shroud are axially movable relative to one another to vary the size of the inlet passage; the nozzle ring having a circumferential array of inlet vanes extending across the inlet passage. The shroud covers the opening of a shroud cavity and defines a circumferential array of vane slots, each vane slot corresponding to an inlet vane, the vane slots and shroud cavity being configured to receive said inlet vanes to accommodate axial movement of the nozzle ring.