Highly efficient neutral and ionic imidazole-based organocatalysts have been developed for the synthesis of cyclic carbonates from epoxides and carbon dioxide. The ionic derivatives performed as bifunctional catalysts and exhibited improved activity for the fixation of CO₂ compared to the neutral compounds. Mechanistic studies revealed that the hydroxyl group promoted the activation of the epoxide facilitating the epoxide ring-opening by nucleophilic attack of the iodide.