Hybrids consisting of poly(ethylene oxide-b-amide-6), PEBAX(TM), and zirconium oxide were prepared from hydrolysis and condensation of zirconium tetraisopropoxide in solution containing the dissolved organic polymer. These hybrids were characterized by thermogravimetric analysis, differential scanning calorimetry, infrared spectroscopy, and electron microscopy. Results show that the incorporation of the inorganic phase seems to promote the degradation of the organic polymer. Composite membranes consisting of a porous support of poly(vinylidene fluoride), PVDF, and a filter layer of PEBAX/ZrO2 were prepared and characterized by electron microscopy. Permeation tests of water or aqueous solutions containing poly(ethylene glycol) of different molar masses were carried out to determine the permeation rate and the membrane cutoff respectively. To determine the phosphate retention, permeation tests using a KH2PO4 aqueous solution were carried out. Independent of composition of the filter layer, values of phosphate retention were nearly equivalent to 80%.