The nanocomposite of polyamide 6 (PA6)/poly(methyl methacrylate) (PMMA)/carboxylic acid functionalized single walled carbon nanotubes (SWCNTs-COOH) was prepared in a weight ratio of 49.5/49.5/1 at 230 degrees C by using melt-mixing method. The PA6/PMMA blend with weight ratio of 50/50 served as reference. The Fourier transform infrared analysis of nanocomposite shows the occurrence of hydrogen-bonding interactions among PA6, PMMA, and SWCNTs-COOH. Thermal studies of nanocomposite exhibited higher thermal stability and increased crystallinity of PA6 in nanocomposite compared to the blend. The X-ray diffraction curve of nanocomposite indicates that the rich aII phase of PA6 was higher compare to the blend. The scanning electron microscope analysis of nanocomposite confirmed that PMMA exhibited as a uniform dispersion and existed as co-continuous phase morphology in a continuous phase of PA6 compared to the blend. Furthermore, the obtained results suggest that the incorporation of SWCNTs-COOH into the PA6/PMMA blend enhances the compatibility as a compatibilizer between the two polymer components. POLYM. ENG. SCI., 2013. (c) 2012 Society of Plastics Engineers