An electrolyser arrangement comprising a water electrolyser having a plurality of electrode plates arranged side-by-side in alternate polarities and each of which is separated by a membrane, at least one aqueous electrolyte inlet, a cathodic outlet, and an anodic outlet; and a U-shaped arrangement, the legs of which each represents a gas receiving chamber, one for receiving hydrogen-containing liquid from the cathodic outlet and the other for receiving oxygen-containing liquid from the anodic outlet, at least one chamber has an inlet receiving liquid from the cathodic or anodic outlet at a point above an electrolyte inlet and a top gas outlet, the bottom of the U-shaped arrangement having at least one outlet feeding electrolyte-containing water to the aqueous electrolyte inlet.