In capillary liquid chromatography (LC), an electrochemical detector with a carbon interdigited array (IDA) microelectrode is used effectively. The IDA electrode is found to be more sensitive than the ordinary glassy carbon electrode in capillary LC. Besides the above advantage, using the IDA electrode, a lower background current and noise level were observed. Using a microflow processor at a flow-rate of 4.4 μl min - 1 , catecholamines and their metabolites (3,4-dihydroxymandelic acid, 3,4-dihydroxyphenylethyleneglycol, vanilmandelic acid, norepinephrine, 3-methoxy-4-hydroxyphenylglycol, 3,4-dihydroxyphenylacetic acid, 3,4-dihydroxybenzylamine, 5-hydroxyindoleacetic acid, vanillacetic acid, homovanillic acid, dopamine and serotonin) were separated in a single run by ion-pair gradient elution. Excellent reproducibility of retention time was obtained with relative standard deviation (R.S.D.) values of 0.5%. The detection limits of catecholamines and their metabolites ranged from 0.19 fmol for 3,4-dihydroxymandelic acid to 3.93 fmol for vanillacetic acid.