Sulfonated resins with a variety of acid-site distribution have been prepared and characterized to obtain highly active immobilized phase-transfer catalysts for conversion of benzophenone azine into hydrazine in a liquid-solid-liquid triphase system. Sulfonation of cross-linked polystyrene with concentrated H 2S0 4 under mild conditions gave various resins of lower acidity, but X-ray microanalysis revealed the acid-site distribution to be like an eggshell, showing that the spheres were sulfonated from the external surface toward a central core. Lipophilic resins with uniform acid-site distribution were obtained by the ternary copolymerization of sodium p-styrenesulfonate, styrene, and divinylbenzene in aqueous dimethylformamide. The acidity of resins could be predicted based on the monomer content in the charge. The competing imbibition of two insoluble liquids, toluene and water, by sulfonated resins balanced at 0.8 meq/g, in good agreement with the optimum acidity for azine conversion. The value corresponds to a sulfonic group per five pendant phenyl groups of the skeletal polymer. Effect of particle size of ternary gel catalyst on the rate of azine conversion suggested the predominant contribution of acidic sites on the surface. Attempts were made to expose available sites on the surface as much as possible employing porous texture under the balanced-wetting environment. Thus moderately sulfonated resins with a macroreticular structure showed high activity for azine conversion. A reactor device capable of continuous operation of liquid-solid-liquid triphase catalysis in a flow system and the results of an illustrative run with 90% conversion over 50 h on-stream are also described.