TiN hard coatings were prepared by arc ion plating with both direct current (dc) and pulsed biases. An extensive investigation was undertaken to determine the effects of the substrate temperature on the mechanical properties and the microstructures of films. The results show that the substrate temperature is decreased evidently when a pulsed bias instead of a do one is employed. At the same time, the microstructures and the properties are also improved. A low-temperature arc ion plating can be realized by using pulsed biases. (C) 2004 American Vacuum Society.