Reactive ion etching of indium-tin oxide at 250 degrees C based on SiCl4, CF4, and CH4 gases has been studied. An etch rate as high as 435 Angstrom/min has been achieved. Depending on process parameters such as temperature, gas, power, and pressure, the etch rate can be controlled by ion bombardment energy alone or by plasma phase chemistry and ion bombardment energy. The bottleneck step of the surface reaction can be the reduction of the metal oxide or the removal of reaction products. These process results are consistent with the surface analysis data. Photoresist can be used as a masking layer in the 250 degrees C plasma etching process when the mask is properly designed and. the feeding gas includes CH4.