A height-adjustable chair column includes a vertical post axially extending along a longitudinal axis, a bottom plate, a guide cylinder bushing permanently inserted into the upper end area of the vertical post, and a guide tube inserted in the guide cylinder bushing so that it is guided with freedom of axial movement and secured against rotation in the guide cylinder bushing. Further, the chair column includes a lockable gas spring assembly with a pressure cylinder, which is installed coaxially in the guide tube such that it is secured against axial displacement relative to the guide tube and it is free to rotate about the longitudinal axis, and with a piston installed in the pressure cylinder with freedom of sliding axially. The piston is connected to a piston rod which is fastened to the bottom plate and supported there with freedom of rotation about the longitudinal axis. Moreover, a height-adjustable foot rest is attached to the upper end region of the guide tube.