[en] IrO₂ nanocrystals (NCs) were deposited on patterned carbon nanotube (CNT) bundle arrays via metal-organic chemical vapor deposition (MOCVD) using (C₆H₇)(C₈H₁₂)Ir as a source reagent. The structural and spectroscopic properties of the IrO₂/CNTs composite were characterized by field-emission scanning electron microscopy, Raman spectroscopy and transmission electron microscopy. The combined effects of the geometrical structure of IrO₂/CNTs, and the natural conducting and enhanced resistance to oxidation properties of IrO₂ lead to a low turn-on field of 0.9 V/μm at a current density of 0.1 μA/cm², a low threshold field of 2.7 V/μm at a current density of 1 mA/cm², a high field enhancement factor of 7.4 x 10³, and long-term stability for the IrO₂/CNTs composite. The results indicate that the IrO₂/CNTs composite can be a potential candidate for field emission devices.