A key operated cylinder lock is disclosed, including a hollow stationary cylinder housing enclosing a turnable power transmission element and a locking bar having a position locking the turning movement of said power transmission element relative to said cylinder housing. The cylinder lock further includes a set of discs including a number of locking discs turnable by means of combination surfaces on a key of said lock, the locking discs being turnable, by the turning movement of said key, from an initial key insertion position to a releasing position, in which the power transmission element is released from its locked connection to the cylinder housing, whereby the key of the lock is arranged to directly transmit a turning force to a number of locking discs only in a direction from said initial position to said releasing position. The returning of these locking discs to their initial position is arranged to be carried out by means of a separate return bar, receiving turning power from said key through one or several members turning with the key. Thereby the lock is operable in both turning directions and, in addition, the correct turning angle, that is the combination value of a number of locking discs, can be different in opposite turning directions. The separate return bar is movable in a circumferential as well as a radial direction of the lock.