The polystyrene based barium phosphate composite membrane was prepared by co-precipitation method. The composite membrane has been characterized on the basis of scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR) and thermo gravimetric analysis (TGA) and differential scanning calorimetry (DSC) studies. Ion-exchange capacity, water uptake, porosity,thickness and stability studies were also carried out to determine the preliminary ion-exchange properties of the composite membrane. The order of transport number of cation for univalent electrolytes solution was found to be KCl < NaCl < LiCl. The antibacterial activity of composite membrane was investigated against some bacteria.