Abstract: The cited electrode was fabricated by dipping a glass substrate precoated with a thin layer of indium tin oxide into a sol gel prepared from CeCl3.7H2O and titanium isopropoxide. The electrode was air-dried then heated at 300°C for 10 min. The resulting CeO2/TiO2 thin-film electrode was used as an amperometric sensor in a flow injection system for monitoring electroinactive monovalent cations, viz., Li, Na, K, ammonium and tetraethylammonium ions. Typically, the sample (50 µL) was injected into an aqueous carrier stream at a flow rate of 1 ml/min and the analyte cation was detected at the thin-film electrode at -0.9 V vs. Ag/AgCl. The calibration graph was linear from 0.4-4 mM Li; the detection limit was 0.02 mM. RSD was 5.7% (n = 8) at the 1 mM level. Similar calibration data were obtained for the other cations studied. The results obtained were comparable to those obtained by conductimetric detection.