The friction and wear of physical vapour deposition TiN coatings and steel vibrating against corundum in distilled water, seawater, and sodium phosphate solutions have been investigated. The coefficient of friction measured on the TiN-coated surface remained at a level of around 0.2 whereas the uncoated steel substrate exhibited a significantly higher friction. The TiN coating appeared to degrade by oxidational wear. The progress of the wear damage was largely influenced by the transfer layer of titanium oxides formed on the corundum counterbody. The narrow transfer layer formed in distilled water caused a premature perforation of the TiN coating due to the reduction of the real contact area. The results showed that this unfavourable wear behaviour can be avoided by adding sodium phosphate to distilled water resulting in an accelerated removal of the transfer layer.