Using distilled water and air lubricants, wear tests of ceramic-cast iron pairs were carried out on a M-200 type ring-block wear tester. For comparison, ceramic-carbon steel pairs were also tested under the same conditions. The worn surfaces of specimens were observed under scanning electron microscope (SEM) and optical microscope. Furthermore, the tribofilms were analyzed by using Auger electron spectroscopy (AES), energy-dispersive X-ray spectroscopy (EDX) and image analysis technique. In the wear tests of Si 3N 4-cast iron pairs lubricated with distilled water, the friction coefficients of the pairs are just 0.02, and the wear rates of ceramic and iron are near zero. The superior tribological characteristics are due to a tribochemical film, which is formed on the wearing surfaces and has sufficient thickness and area. However, in the test of a Si 3N 4-carbon steel pair lubricated with distilled water, the friction coefficient is still high because the tribochemical film formed on the wearing surface is too thin and too small. A metal transfer film is formed on the ceramic surface when the ferrous metals slide against Al 2O 3. In this situation, the wear amount of Al 2O 3 is quite small, but the wear amount of the metals is large and the friction coefficient is rather high.