A thermopile transducer made from 76 bismuth/antimony thin-film thermocouples is used for the measurement of heat output from chemical reactions. The method is independent of optical transmission and, therefore, applicable in strongly absorbing or particle-containing liquids. Thermoelectrical voltages up to 30 mV have been measured in sample volumes up to 20 μl. The influence of the size and shape of the reaction drops can be controlled by modification of the surface and internal electrical calibration. Cerium is detected down to amounts of 5 nmol (7 μg, 0.25 mmol 1 - 1 ). A further improvement of the analytical limit down to the 10 pmol (0.5 nmol 1 - 1 ) range seems realistic.