The invention relates to a diffuser for the exhaust section of a gas turbine, comprising at least one cone extending along a machine axis and bordering a channel for an exhaust flow, whereby said at least one cone has a wall with an internal structure comprising a plurality of longitudinal liner segments extending in an axial direction and establishing a conical liner being in contact with the exhaust flow, a support structure coaxially arranged with respect to said conical liner in a predetermined distance, and an insulation filling the space between said conical liner and said support structure. A smooth inner surface and a safe compensation of different thermal expansions are achieved by having each of said liner segments fixed in a lateral direction at one fixing point, and having each liner segment supported at a plurality of distributed points outside said fixing point by means of supporting elements, which are confined to the space between said conical liner and said support structure and allow for a lateral thermal expansion of the liner segments.