Polyacrylic acid/polyethersulfone (PAA/PES) capsules were adopted as templates to synthesize PAA/PES core–shell spheres, and the PES shell of spheres could be removed automatically by the swelling nature of the cross-linked PAA hydrogel core. By using the method, PAA hydrogel spheres were prepared with an ultrahigh ion exchange capacity of 12 meq g−1, and the spheres showed a high adsorption capacity for methylene blue. The PAA-polyacrylamide hydrogel spheres with dual adsorption ability and good mechanical property were also prepared. It was revealed that these two hydrogel spheres can be effectively utilized in the removal of environmental toxins.