Disclosed is a shell side contactor which can be used to form ozonated water. The contactor includes a shell and a plurality of porous perfluoroalkoxy resin thermoplastic hollow fibers that are potted at each end of the shell. The perfluoroalkoxy resin hollow fibers can be unskinned, skinned on their inner surface, or skinned on their outer surfaces. The contactor is provided with a spacer that spreads the hollow fibers adjacent an inlet to the shell, thereby permitting liquid flow at desirably high flow rates with acceptable pressure drop through the shell. The mass transfer efficiency of the contactor can be enhanced by jetting water into the fiber bundle and introducing gaps into the bundle.