A machine for the liquid or gaseous treatment of textiles or other fibrous or porous materials, which comprises a partition (9) located in its end zone opposite its cover (2), which partition (9) forms, with the bottom of the machine (1) and the corresponding part of its side walls (14), a leaktight box which delimits an expansion zone for the treatment fluid, that part of the machine which is located between the cover (2) and the partition (9) forming the actual treatment zone (10), which accommodates at least one holder for the material, the machine further comprising a device for the circulation of the treatment fluid.