The performance of the Servounex DCL 101 paramagnetic analyzer has been studied. The apparatus is resistant to shock and there is little drift. More than 99.9 per cent response is obtained with a flow of 200 ml/min of gas for 1 minute, or by the injection of 100 ml from a syringe. The instrument examined had a small electrical non-linearity error not exceeding 0.11 per cent. The remaining disagreement with chemical methods of analysis did not exceed 0.07 per cent of the sampled volume. The apparatus may be used for analysis of samples containing nitrous oxide without loss of accuracy.