Two clay compounds, montmorillonite (Cloisite 30B) and kaolinite, were dispersed in a poly(m-xylene adipamide) resin at loading levels of 2 wt % clay. The samples were melt-compounded and extruded. The extruded samples were injection-molded into preforms and then blow-molded into multilayer bottles. Rheology, calorimetry, electron microscopy, and gas-transport measurements were performed. Both clays were nucleating agents, giving crystallite sizes that did not cause haze. Kaolinite was more difficult to exfoliate than montmorillonite, and under similar processing conditions, kaolinite resulted in a higher degree of crystallinity. Both nanocomposites exhibited improved gas-barrier properties over the neat resin. (c) 2007 Wiley Periodicals, Inc.