The major goal of this work was to develop a new solid-state electrochemiluminescence (ECL) detector suitable for capillary electrophoresis (CE). The detector was fabricated by coating a sol-gel derived zirconia (ZrO2)-Nafion composite film on a graphite electrode, then the zirconia-Nafion modified electrode was immersed in tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)) solution to immobilize this active chemiluminescence reagent. The voltammetric and ECL behaviors of the detector were investigated and optimized in tripropylamine solution. The ratio of 53% for zirconia in the zirconia-Nafion composite provided the highest luminescence intensity of immobilized Ru(bpy)(3)(2+). The ECL can maintain its stability very well in the phosphate solution in the period of 5-90 h when the solid-state ECL detector was immersed in the solution all the time. The optimum distance of capillary outlet to the solid-state ECL detector has been found to be ca. 50-80 Pm for a 75 μ m capillary. The effects of ionic strength and pH of ECL solution on peak height were investigated. The CE with solid-state ECL detector system was successfully used to detect tripropylamine, lidocaine, and proline. The detection limits (S/N = 3) were 5 x 10(-9) mol(.)L(-1) for tripropylamine, 1 x 10(-8) mol(.)L(-1) for lidocaine and 5 x 10(-6) mol(.)L(-1) for proline, and the linear ranges were from 1.0 x 10(-8) to 1.0 x 10(-5) mol(.)L(-1) for tripropylamine, 5.0 x 10(-7) mol(.)L(-1) to 1.0 x 10(-5) mol(.)L(-1) for lidocaine and 1.0 x 10(-5) to 1.0 x 10(-3) mol(.)L(-1) for proline, respectively.