Abstract: An adjustable oleopneumatic support, particularly for the height adjustment of the seats of office chairs with central columns, is disclosed. The oleopneumatic element includes a hollow cylindrical body with a packing member realizing an upper and a lower cavity, the respective lower end being rigidly linked to the base of the chair, and a coaxial hollow stem, the head of which is rigidly linked to the seat of the same chair, the hollow coaxial stem being rigidly connected to a piston which defines inside the upper cavity two chambers, an upper and a lower chamber, respectively, both containing fluid; the hollow coaxial stem is provided inside with valvular coaxial actuation means controlling a passage for a hydraulic fluid, the respective outlets being placed above and below the piston, respectively; the lower cavity being able to contain compressed gas.