A novel sensor have been constructed by layer-by-layer hybridizing phosphomolybdate (POM) and poly(ferrocenylsilane) (PFS) on a cysteamine modified gold electrode. The properties and performance of the sensor have been measured by electrochemistry and atomic force microscopy in detail. The results showed that the constructed multilayers modified gold electrode combined the properties of POM and PFS, and exhibited good electrocatalytic ability to a series of inorganic ions, including BrO , ascorbic acid and SO 2À 3 . The well catalytic activity of the sensor was ascribed to the porous structure of hybrid POM-PFS multilayer. The resulted sensor exhibited extremely fast amperometric response, low detection limit, high selectivity and wide linear range to these analyses.