Batch and continuous-flow measurements of codeine were performed by electrochemiluminescence, using a miniaturized sensor combining transduction electrodes and a photodetector on the same silicon chip. In the case of flow measurements, a flow channel was additionally integrated on chip using the EPON SU-8 technology. Three different ruthenium complexes have been tested as co-reactants and compared to a commercially available ruthenium (II) tris(2,2'-bipyridyl) complex [Ru(bpy)3 2+]. All synthesized compounds exhibited similar electrochemical properties and emission spectra. Concerning the ability of the synthesized complexes to catalyze electrochemiluminescence in the presence of codeine, best results were achieved using ruthenium (II) bis(2,2'-bipyridyl) (1,10-phenanthroline) dichloride tris-hydrate [Ru(bpy)2(phen)2+] as light intensity was 2.5-times higher than that obtained with Ru(bpy)3 2+. In batch mode and flow injection analysis, a detection limit of 0.1 and 50μM was found, respectively. The linear ranges extended over 2 or 3 decades and reproducibility of the assays was satisfactory. Codeine measurements were successfully performed in pharmaceutical samples. Copyright (C) 1999 Elsevier Science B.V.