A ternary Co-P-B amorphous alloy catalyst was prepared by chemical reduction with the mixed KBH4 and NaH2PO2 in aqueous solution, and was characterized by ICP, XRD, SAED, TEM, SEM, XPS, H-2-TPD and hydrogen chemisorption. During liquid phase hydrogenation of maltose, the as-prepared Co-P-B catalysts exhibited 100% selectivity to maltitol and much higher activity than the Co-B, Co-P and Raney Ni, apparently owing to the synergistic promotions of the alloying B and P. More specifically, the alloying B increased the number of active sites (S-act) and donated partial electrons to the Co, which was favorable for the hydrogenation of the C=O group in the maltose. Furthermore, the alloying P led to the enhancement of the intrinsic activity (R-H(S)) by forming new Co clusters as active sites. The maximum activity was obtained on the Co72.2P5.9B21.9. (C) 2007 Elsevier B.V. All rights reserved.