Turning experiments have been carried out on a low carbon iron using steel tools of different side rake face geometry. Temperature distributions have been determined using a recently developed metallographic method. It has been found that when using tools which have a controlled chip-tool contact length of 0.5 mm. the temperatures are ∼30 per cent lower than when using conventional, 6 deg rake tools and, as a result, tool life is longer. Theoretical equations are described which allow the calculation of the temperature distribution along the chip tool interface and the tribological conditions in this region are also considered in detail. There is good agreement between the calculated and measured temperature distributions.