An analyser for the simultaneous determination of carbon, hydrogen and nitrogen in organic compounds is described. The samples are burned in a static system in oxygen and the combustion products are determined using a self-integrating thermal conductivity method. Up to 16 previously weighed samples of 0.5 ÷ 2.0 mg are analysed without any manual help and the results are presented in digital form. One determination takes between 7 and 13 minutes. At present the standard error of a single determination is 0.20, 0.08 and 0.30% (absolute) for carbon, hydrogen and nitrogen, respectively, but these figures may easily be improved by minor modifications.