Unit and method for applying a wall to a hollow body in a manufacturing process for producing a beverage capsule; are provided: a sealing conveyor which advances along a sealing path; a sealing head conveyed by the sealing conveyor and which supports a gripping device for gripping the wall and a retaining device suited to retain the hollow body; a first feed station for feeding the wall to the sealing head, so that the wall is gripped by the gripping device; and a second feed station arranged downstream from the first feed station along the sealing path, for feeding the hollow body to the sealing head, so the hollow body is coupled to the wall gripped by the gripping device, and is retained by the retaining device.