A connecting coupling has a hose nozzle and a coupling piece, for joining hose lines, and in particular for pressure-tight connection of the hose line of a dishwashing sprayer to a single-lever pillar mixer by means of plug-in connection. To further reduce manufacture costs and at the same time achieve a rapid and easily detachable connecting union, in the connecting coupling a retaining element is a disk-shaped body, split on one side, with a reinforced outer rim and with segment-like holding and blocking tongues that define a rectangular opening cross-section when the retaining element is closed. A coupling piece has a middle tube section with an end section, which can be inserted into the mixer, and the hose nozzle carries an O-ring on its end, secured by a bushing, and the bushing is locked by a retaining ring, to which is connected a plastic part with a retaining groove.