Iridium acetylacetonate, dicarbonylacetylacetonato iridium, and tetrakisiridium dodecacarbonyl (iridium carbonyl) have been evaluated for metallorganic chemical vapor deposition (CVD) of pure iridium films. Temperature programmed mass spectroscopy reveals that iridium tris-acetylacetonate and dicarbonylacetylactonato iridium have high thermal stability and sublime at 200 and 100 °C in vacuum, respectively. Iridium carbonyl decomposes upon sublimation at temperatures above 120 °C. Pure CVD Ir films were obtained using iridium carbonyl; however, carbon is incorporated into the iridium films with the iridium trisacetylacetonate and dicarbonylacetylactonato iridium precursors unless a reactive gas, such as oxygen is co-dosed. Co-dosed oxygen also increases the film deposition rate and significantly decreases the film growth temperatures. Particles were found on the films grown with iridium carbonyl between 280 to 400 °C, indicating that gas phase nucleation occurred during deposition.