Abstract: The tribological properties of Ti₃SiC₂, stainless steel and NiCr alloy under dry sliding, in distilled and sea water were investigated on an SRV-1 tribometer. The worn surfaces were analyzed by using scanning electron microscopy and X-ray photoelectron spectrometer. The results show that the friction coefficient of Ti₃SiC₂/Al₂O₃ tribo-pair was insensitive to sliding condition. The wear rate of Ti₃SiC₂ in liquids (distilled water and sea water) was one order of magnitude lower than that under dry sliding. In the competition between the two wear mechanisms of mechanical wear and tribo-oxidation wear, mechanical wear was the dominant mechanism, which was independent on the sliding condition. So the friction coefficient and wear were high for Ti₃SiC₂/Al₂O₃ tribo-pair under the three sliding conditions. Tribological properties of stainless steel/Al₂O₃ and NiCr alloy/Al₂O₃ were sensitive to sliding condition. The friction coefficient and wear rate of stainless steel and NiCr alloy successively decreased in the order of dry sliding, distilled water, and sea water. The degree of decrease was the largest for NiCr alloy/Al₂O₃ tribo-pair. Under dry sliding mechanical wear was the dominant wear mechanism for both the tribo-pairs. In distilled water both mechanical wear and tribo-oxidation wear worked. In the sea water corrosion wear was the main wear mechanism. The tribo-corrosive products (FeCl₂, CrCl₃ or CrO₂^2- and CrO₄^2-) were lubricants to decrease the friction and wear.