A series of polyamide 6 nanocomposites (NC) and PA6/TPU/clay nanocomposite blends (NCB) were prepared from commercial polyamide 6, synthesized thermoplastic polyurethanes and two types of organically modified montmorillonites - Cloisite® 10A and Cloisite® 20A. The thermal behavior was examined by non-isothermal thermogravimetry (TG, DTG), differential scanning calorimetry (DSC) and dynamic-mechanical thermal analysis (DMTA). It has been proved that the thermal stability and tensile properties of these new systems were greater when the organoclay was present within the polymer matrix. What more these properties depend on both the OMMT loading and the type of the gallery cations of organically modified montmorillonites.