Abstract: The present invention discloses an adjustable office chair in which the backrest may be adjusted in relation to the seat carrier. This adjustment is realized by means of an actuating lever and a clamping bolt arrangement which allows a linkage system to vary the position of the backrest in relationship to the seat. Once a desired relationship between the two parts is realized, the actuating lever is released and the linkage system is locked into a fixed position. This arrangement is realized by providing a spring system which displaces a clamp bolt in its longitudinal direction relative to the parts to be immobilized. The actuating lever, when activated, acts on a thrust bearing of the clamp bolt and displaces the clamp bolt into the release position.