A new complex of cerium(III) [Ce(III)] with gelatin has been prepared in an aqueous solution. The FTIR, UV-vis, and XRD studies of the Ce(III)-gelatin complex revealed that the carboxyl groups of gelatin coordinated to Ce(III). The thermal property of the complex was investigated by thermo gravimetric analysis. It was discovered that the thermally decomposed rate of the complex decreased obviously. In addition, the antimicrobial activity of the complex to Staphylococcus aurens, Pseudomonas aeruginosa, and Escherachia coli was measured and found that its minimal inhibitory concentration (MIC) to the growth of bacterium was 350 mu g/mL, which was almost the same as Ce(III) ion. (C) 2008 Wiley Periodicals, Inc.