The present invention relates to an assembly for the preparation of a heated beverage, comprising a case or cover or box (battery cover) (8) for mobile phone (60) or external device (6) comprising an internal seat for the corresponding insertion of at least a container (7), said container (7) comprising means (13) for the production of heat, wherein said container (7) comprises contacts (12) to electrically feed said means (13) when said container is inserted in the seat.