Polymer-encapsulated ion-exchange resins are disclosed. The resins are useful in adsorption, catalysis, and other applications. Catalysts comprising a polymer-encapsulated combination of an ion-exchange resin and a transition metal are also disclosed. The catalysts are useful in hydrogenation, oxidation, hydroformylation, polymerization, and other valuable processes. Certain of the polymer-encapsulated catalysts enhance the productivity in the process for producing hydrogen peroxide from hydrogen and oxygen.