SummaryTwo glass capillary gas chromatographic systems were equipped with inert effluent splitters which allowed simultaneous data acquisition using nonspecific and element-specific detectors. Simultaneous detection was achieved using the nonspecificflameionizationdetector(F1D) and the Hall' electrolytic conductivity detector (HECD) operated in either the sulfur-or the nitrogen-specific mode. Typical application of the simultaneous detection system as applied to analysisof petroleum residues is briefly described. The Hall electrolytic conductivity detector can be made element specific for halogen-, sulfur-, or nitrogen-containing compounds. Simultaneous detection enhances the information yield from a single sample injection and proves to be a powerful complementary technique when used with computerized gas chromatography/mass spectrometry.