A method for single-cell analysis was developed by combining capillary zone electrophoresis (CZE) with electrochemical detection (ECD) using a dual electrode consisting of two different types of electrode material (carbon fiber and Au/Hg). In this method, the parallel mode was used. Different potentials were applied to both electrodes of the dual electrode. Tryptophan and glutathione, which could not be simultaneously detected by normal CZE-ECD, could be simultaneously and selectively detected by CZE-ECD at the dual electrode in one run, respectively. The CZE-ECD system with the dual electrode was applied to determine them in individual rat hepatocytes.