A safe (1), substantially box-like in shape, which is provided with a door (2) that is hermetically sealed and defines, in a portion thereof, a cavity (3) for accommodating a closing assembly (4). The assembly (4) comprises at least one sliding latch (5), which can perform a translational motion from a configuration of complete accommodation, in the cavity (3), to one of protrusion from at least one edge (6) of the door (2), and electrical movement means (7) for the translational motion of the at least one sliding latch (5). The cavity (3) is provided with a seat (8) for the stable accommodation of a cylinder (9) of standardized type actuated by a corresponding key. The bit (10) of the cylinder (9) can face and be proximate to at least one laminar element (11), which is arranged parallel to the door (2) and is integral with the at least one sliding latch (5). The laminar element (1 1) can be functionally associated with the electrical movement means (7). The rotation of the bit (10), following the rotary movement of a key, and/or the actuation of the electrical movement means (7), determine a translational motion of the at least one laminar element (1 1) with consequent translational motion of the at least one sliding latch (5).