A reverse osmosis/nanofiltration technique was applied to recover the soluble catalyst-sodium salt of tetra(sulfophthalocyanine)-cobalt(II)-from the reaction solutions in the liquid phase oxidation of sodium sulfide. Conditions for the efficient recovery of the catalyst were determined. A catalyst recovered by reverse osmosis/nanofiltration retains its activity and selectivity, and can be re-used in the reaction. A catalytic membrane was prepared by adsorption of the Co-TSPC catalyst over a porous membrane. Advantages of using the membrane as a catalyst support were demonstrated.