Mixed salts of silver and ammonium derivatives Ag-x(NH4)(5-x)PMo10V2O40 (x = 0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5,4.0,4.5, 5.0) were designed and synthesized through ion exchange along with precipitation. Different molar ratio of Ag+ to NH4+ resulted in different surface areas, which could give different oxidative catalytic activity in oxidation of starch. Among all molybdovanadophosphoric salts, Ag-3.5(NH4)(1.5)PMo10V2O40 was found to be the most active catalyst in starch oxidation with the highest degree of substitution (DS = 0.62 mol/100 g). And Ag-3.5(NH4)(1.5)PMo10V2O40 could be reused several times without significant loss of its catalytic activity. (C) 2013 Elsevier B.V. All rights reserved.