(Carboxy-3-oxopropylamino)-3-propylsilylcellulose (COPAPSC), a novel organocatalyst, has been prepared by a synthesis grafting of –COOH functionalized organosilanes on a cellulose using surface hydroxyl groups as anchor points. The –CO₂H group-functionalized cellulose was synthesized via the consecutive surface functionalization with 3-aminopropyltriethoxysilane (3-APTES) followed by the condensation of the surface –NH₂ groups with succinic anhydride. COPAPSC is used as a catalyst for the synthesis of tri- and tetra-substituted imidazoles from the reaction of benzil, aromatic aldehydes, ammonium acetate, and amines under solvent-free conditions. The key advantages of this process are high yields, easy work-up, purification of products by non-chromatographic methods and the reusability of the catalyst.