The determination of carbon in soils using the Leco CR‐12 resistance furnace has been investigated. The microprocessor‐ controlled furnace, and aspects of its use and performance, are described with particular attention to the routine analysis of soil materials. Some of the effects of furnace temperature, sample weight, fine grinding, ‘comparator’ setting and nature of the carbon on carbon determination and analysis time have been investigated on a range of soils. The furnace method has been compared with a wet oxidation technique and the possibility of characterization of soil carbon ‐ organic and inorganic ‐ was briefly investigated.