A device for releasing a cold room sliding door from its closed position, comprising: - a bush incorporated into the thickness of the door panel and fixed to the door panel such that its axis is perpendicular to this latter; - a central shaft coaxially and rotatably inserted into the bush; the central shaft is able both to rotate about the axis of the bush and to move along said axis; whereby means (26, 24; 27, 24) for guiding the movement and rotation of the central shaft, which enable it to rotate in the direction compatible with the door opening direction are provided; wherein the guide means for the central shaft comprise two opposing guides (26; 27) provided in the inner wall of the bush, and respective pawls projecting radially from the central shaft and cooperating with the guides (26; 27), the guides (26; 27) having an inclination to the bush axis which is compatible with the door opening direction; whereby a preloaded helical spring is resting with one end on a collar of the central shaft whereas its other end rests against a step in the interior of the bush; and whereby - external means, e.g. external handle, for rotating the central shaft are provided; - internal means, e.g. internal handle, for rotating the central shaft are provided and said internal means are provided with a striker adapted to come into contact with a fixed point, e.g. a door frame upright, such that, following forced rotation, achieved by said external means or internal means, of the central shaft in the direction compatible with the door opening direction, a consequent forcing of said striker against said fixed point is obtained, such as to cause release of the door; characterised in that the bush has a length less than the thickness of all or at least part of the door panels of such doors, a ring cap being provided coupleable coaxially to the bush such that the bush -ring cap assembly has a length adapted to the thickness of the specific door panel wherein the coupling between the ring cap and bush is of "telescopic" type, means being provided to fix the ring cap to the bush such as to obtain the required length of the bush -ring cap assembly. - a bush incorporated into the thickness of the door panel and fixed to the door panel such that its axis is perpendicular to this latter; - a central shaft coaxially and rotatably inserted into the bush; the central shaft is able both to rotate about the axis of the bush and to move along said axis; whereby means (26, 24; 27, 24) for guiding the movement and rotation of the central shaft, which enable it to rotate in the direction compatible with the door opening direction are provided; wherein the guide means for the central shaft comprise two opposing guides (26; 27) provided in the inner wall of the bush, and respective pawls projecting radially from the central shaft and cooperating with the guides (26; 27), the guides (26; 27) having an inclination to the bush axis which is compatible with the door opening direction; whereby a preloaded helical spring is resting with one end on a collar of the central shaft whereas its other end rests against a step in the interior of the bush; and whereby - external means, e.g. external handle, for rotating the central shaft are provided; - internal means, e.g. internal handle, for rotating the central shaft are provided and said internal means are provided with a striker adapted to come into contact with a fixed point, e.g. a door frame upright, such that, following forced rotation, achieved by said external means or internal means, of the central shaft in the direction compatible with the door opening direction, a consequent forcing of said striker against said fixed point is obtained, such as to cause release of the door; characterised in that the bush has a length less than the thickness of all or at least part of the door panels of such doors, a ring cap being provided coupleable coaxially to the bush such that the bush -ring cap assembly has a length adapted to the thickness of the specific door panel wherein the coupling between the ring cap and bush is of "telescopic" type, means being provided to fix the ring cap to the bush such as to obtain the required length of the bush -ring cap assembly.