The title complexes, (eta(4) -cycloocta-1,5-diene)bis(1,3-dimethylimidazol-2-yl-idene)iridium(I) iodide, [Ir(C5H8N2)(2)(C8H12)]I, (1) and (eta(4)-cycloocta-1,5-diene)bis(1,3-diethylimidazol-2-ylidene)iridium(I) iodide, [Ir(C7H12N2)(2)(C8H12)]I, (2), were prepared using a modified literature method. After carrying out the oxidative addition of the amino acid l-proline to [Ir(COD)(IMe)(2)]I in water and slowly cooling the reaction to room temperature, a suitable crystal of 1 was obtained and analyzed by single-crystal X-ray diffraction at 100 K. Although this crystal structure has previously been reported in the Pbam space group, it was highly disordered and precise atomic coordinates were not calculated. A single crystal of 2 was also obtained by heating the complex in water and letting it slowly cool to room temperature. Complex 1 was found to crystallize in the monoclinic space group C2/m, while 2 crystallizes in the orthorhombic space group Pccn, both with Z = 4.