Nylon 6,6 polymer and cobalt-manganese oxide nanoparticles (Co-Mn NPs)/nylon 6,6 nanocomposites were prepared by solution casting method. The morphological study illustrated that the Co-Mn NPs were well dispersed within the membrane. The differential scanning calorimetry (DSC) analyses presented that the melting temperature (T-m) and crystallization temperature (T-c) of Co-Mn NPs/nylon 6,6 membranes were higher than neat nylon 6,6, while the mechanical properties of nanocomposite membranes were lower than neat nylon 6,6. The nanocomposite and neat nylon 6,6 membranes were also used for the decolorization of alizarin red dye in an aqueous medium as a function of time. It was found that about 70-83% of dye was decolorized within 150min using nanocomposite membranes.