The manuscript reports the synthesis of a polymeric calix[4]resorcinarene catalyst incorporated with N‐propyl sulfamic acid and the catalytic synthesis of 1,8‐dioxo‐octahydroxanthenes by this polymeric catalyst. Highly cross‐linked porous organic polymers as a class of amorphous and nano‐scale porous polymeric networks have been playing a key role in the development of organic synthesis and catalytic systems. The catalyst synthetic steps include (1) the synthesis of calix[4]resorcinarene, (2) polymerization with formaldehyde, (3) modification with 3‐(triethoxysilyl)propylamine (APTES), and finally (4) modification in the presence of chlorosulfonic acid to produce an efficient heterogeneous acidic catalyst for being applied in the condensation reaction of dimedone with divergent aryl aldehydes for synthesizing a series of 1,8‐dioxo‐octahydroxanthenes. This newly synthesized catalyst was characterized by some spectroscopic methods such as Fourier‐Transform Infrared spectroscopy (FT‐IR), elemental analysis (CHNS), field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), gas adsorption/desorption Brunauer‐Emmett‐Teller (BET) methodology, and thermogravimetric analysis (TGA) and its recyclability was successfully proved. Solvent‐free conditions, easy reaction handling and work up, mild acidic conditions, green and affordable methodology, gaining high yields of products in short reaction times, and also the catalyst reusability, are the most important advantages of the present method. POLYM. ENG. SCI., 58:1362–1370, 2018. © 2017 Society of Plastics Engineers