Nanocomposites containing nylon 66 and montmorillonite clay organically modified with quaternary ammonium salts were obtained via direct melt intercalation. A montmorillonite sample from Boa Vista/PB, Northeast of Brazil, was treated with three types of quaternary ammonium salts such as Genamin, Praepagen and Cetremide. After the treatment, the powder was characterized by X-ray diffraction (XRD). The produced nanocomposites were characterized by Torque Rheometer, Infrared Spectroscopy (FTIR), mechanical properties and HDT. The obtained results for rheological characterization showed that the nanocomposites did not present deterioration with the presence of modified clay. Generally, the mechanical properties of tensile of the systems presented superior values compared to that of pure Ny 66. HDT's properties presented very interesting values for the nanocomposites and significantly larger than for pure nylon 66.