A spray gun and a detachable liquid reservoir releasably attached to the spray gun by engagement of mateable, non-threaded formations provided on the spray gun and the reservoir. The spray gun has an integral connector boss with a socket for reception of a connector tube of the reservoir. The boss has an external flange at the distal end and the reservoir has hook members separate from the connector tube. The hook members are co-operable with the flange when the connector tube is received in the socket to secure releasably the reservoir to the spray gun. In another arrangement, the connector tube is an interference friction-fit in the socket to secure releasably the reservoir to the spray gun. In yet another arrangement, the connector tube has bayonet lugs co-operable with bayonet grooves in the wall of the socket when the connector tube is received in the socket to secure releasably the reservoir to the spray gun. In a still further arrangement, the reservoir has an integral spout received in the socket integral with the spray gun and provided with a helical projection co-operable with the underside of a radial lug externally of the socket to secure the reservoir.