This paper describes the "one-step" bio-reduction synthesis method (using sinensis extract) for the preparation of Au and AgAu catalysts supported on SiO2-Al2O3 (SA) material and their catalytic activity in the oxidation and hydrogenation of CO. For comparison the catalytic activity over reference Au/SA catalyst prepared by conventional deposition-precipitation (DP) method was included. The catalysts have been proved effectively as catalysts in the hydrogenation and oxidation of carbon monoxide in comparison with the sample prepared by DP procedure. The bimetallic AgAu/SA sample showed better behaviour in the CO oxidation, while in the CO hydrogenation reaction was the Au/SA monometallic sample which showed superior catalytic performance. Ours results showed that "one-step" bio-reduction synthesis method have proved to be uncomplicated, cost effectiveness and environmental friendly, that we expected this approach can be efficient to obtain nanostructured-supported Au and AgAu catalysts, with lower crystal size, homogeneous morphology and high catalytic performance and stability in the reactions involving the CO. (C) 2009 Elsevier B.V. All rights reserved.