[reaction: see text] A high-loading ROMPgel-supported thiazolium iodide was prepared via ROMPolymerization of the corresponding norbornene-derived monomer. The resulting ionic ROMPgel proved to be an efficient organic catalyst for Stetter reactions. The 1,4-dicarbonyl products, important intermediates in the synthesis of cyclopentenones and heterocycles, were obtained in high yields and excellent purities after minimal purification. The ROMPgel could be reused in up to four consecutive reaction cycles without significant loss of catalytic activity.