Highly conductive iridium oxide, IrO2, thin films have been successfully deposited on Si (100) substrates by reactive pulsed laser ablation from a metal iridium target in an oxygen atmosphere. By investigating the effects of both the oxygen pressure and the substrate temperature on the properties (namely structure, morphology, and electrical resistivity) of IrO2 films, optimum parameters have been identified for the growth of high-quality IrO2 films. At 200 mTorr of oxygen ambient pressure, IrO2 films deposited at substrate temperatures in the 100-550 degrees C range are polycrystalline with a preferred (101) orientation and exhibit a uniform and densely packed granular morphology with an average feature size increasing (from about 90 to 170 nm with the substrate temperature. The room-temperature resistivities of these IrO2 films compare well with those of bulk single-crystal iridium dioxide. IrO2 films with a resistivity of 39 +/- 4 mu Omega cm are obtained at a substrate temperature as low as 400 degrees C. When the substrate temperature is varied from 300 to 550 degrees C, the resistivity Variations of IrO2 films are correlated to the observed changes in the film morphology.