Roll-off container for the collection of materials, comprising: a substantially parallelepiped containment box, extending longitudinally between an its own front end and an its own rear end; a loading chamber defined at one of said front and rear ends, having an inlet opening made in a front wall of the containment box and downwardly bounded by a access threshold; at least one access door arranged in correspondence with the loading chamber and movable between an open position in which it enables access to the loading chamber through the inlet opening, and a closed position in which it extends parallel to the front wall to close access to the loading chamber; a loading/unloading hook rotatably engaged with respect to the front wall near the access threshold, and movable around a horizontal hinging axis between a rest position in which it is lowered and a working position in which it is raised; at least one locking pin slidably inserted through at least one restrain bracket integral with the front wall near the access threshold, to hold the loading/unloading hook in the work position; locking devices of the door in the closed position, characterised in that said locking devices comprises: at least one guide plate integral with the front wall and slidingly engaging the locking pin, to guide it between an insertion position in which the locking pin extends through the guide plate and the restrain bracket, and an extraction position in which the locking pin is disengaged from the restrain bracket; an auxiliary bracket projecting from the lower part of the access door and insertable in an admittance space defined between the guide plate and the restrain bracket, to be engaged by the locking pin in the insertion position. a substantially parallelepiped containment box, extending longitudinally between an its own front end and an its own rear end; a loading chamber defined at one of said front and rear ends, having an inlet opening made in a front wall of the containment box and downwardly bounded by a access threshold; at least one access door arranged in correspondence with the loading chamber and movable between an open position in which it enables access to the loading chamber through the inlet opening, and a closed position in which it extends parallel to the front wall to close access to the loading chamber; a loading/unloading hook rotatably engaged with respect to the front wall near the access threshold, and movable around a horizontal hinging axis between a rest position in which it is lowered and a working position in which it is raised; at least one locking pin slidably inserted through at least one restrain bracket integral with the front wall near the access threshold, to hold the loading/unloading hook in the work position; locking devices of the door in the closed position, characterised in that said locking devices comprises: at least one guide plate integral with the front wall and slidingly engaging the locking pin, to guide it between an insertion position in which the locking pin extends through the guide plate and the restrain bracket, and an extraction position in which the locking pin is disengaged from the restrain bracket; an auxiliary bracket projecting from the lower part of the access door and insertable in an admittance space defined between the guide plate and the restrain bracket, to be engaged by the locking pin in the insertion position. at least one guide plate integral with the front wall and slidingly engaging the locking pin, to guide it between an insertion position in which the locking pin extends through the guide plate and the restrain bracket, and an extraction position in which the locking pin is disengaged from the restrain bracket; an auxiliary bracket projecting from the lower part of the access door and insertable in an admittance space defined between the guide plate and the restrain bracket, to be engaged by the locking pin in the insertion position.