Described is a cylinder (1) for high pressure compressed fluids comprising a first hollow body (2) having an opening (2a) towards the outside (100) forming with the relative internal cavity a first housing space (2b) for a compressed fluid; at least one second hollow body (3) having an opening (3a) towards the outside (100) and forming with the relative internal cavity a second housing space (3b) for a compressed fluid which is separate and different from the first housing space (2b). The second hollow body (3) is housed inside the first hollow body (2) in such a way as to define a first housing chamber (6) and a second housing chamber (7). The first and second chambers (6, 7) have, respectively, an opening (2a, 3a) towards the outside (100) at the head end (4) of the cylinder (1) and at least the first or the second hollow body (2, 3) has at a bottom end (5) a bottom opening (“C”) which is normally closed.