Novel ternary complex of Eu3+ with N-propyl-4-carboxyphthalimide (NP) and 1,10-phenanthroline (Phen) has been prepared and characterized by means of infrared spectrophotometer (FTIR) and H-1-NMR. Furthermore, its silica-based composites have been prepared via a sol-gel approach. The luminescence properties of the lanthanide complex as well as its silica-based composites have been investigated by means of spectrofluorimeter and phosphorimeter. The results indicated that the resulting transparent organic-inorganic composites provided strong red emission under UV light irradiation even at low concentration of lanthanide complex, e.g. 0.02 mol%. By comparison with ternary lanthanide complex, the silica composites showed fewer emission lines and longer lifetime. (C) 2002 Elsevier Science B.V. All rights reserved.