The covalently immobilized of Saccharomyces cerevisiae alcohol dehydrogenase (SCAD) to magnetic Fe(3)O(4) nanoparticles via glutaraldehyde coupling reaction was studied. The magnetic Fe(3)O(4) nanoparticles were prepared by hydrothermal method using H(2)O(2) as an oxidizer. Functionalization of surface-modified magnetic particles was performed by the covalent binding of chitosan onto the surface. The amino functional group on the magnetic Fe(3)O(4)-chitosan particles surface and the amino group of the dehydrogenase were coupled with glutaraldehyde. The immobilization process did not affect the size and structure of magnetic nanoparticles. For the reduction of phenylglyoxylic acid by immobilized SCAD, the kinetic analysis data indicated that the immobilized SCAD retained 48.77% activity of its original activity. The activation energy within 20-40 degrees C, the maximum specific activity and the Michaelis constants for phenylglyoxylic acid were 7.79 KJ mol(-1), 279.33 nmol min(-1) and 37.77 mmol l(-1), respectively. Furthermore, the immobilized SCAD enhanced thermal stability and good durability in the repeated use after recovered by magnetic separations.