An interfacial polymerization method for nylon 6,6 was adapted to produce nanocomposites with single wall carbon nanotubes (SWNT) via in situ polymerization. SWNT were incorporated in purified, functionalized or surfactant stabilized forms. The functionalization of SWNT was characterized by FTIR, Raman spectroscopy and TGA and the SWNT dispersion was characterized by optical microscopy before and after the in situ polymerization. SWNT functionalization and surfactant stabilization improved the nanotube dispersion in solvents but only functionalized SWNT showed a good dispersion in composites, whereas purified and surfactant stabilized SWNT resulted in poor dispersion and nanotube agglomeration. Weak shear flow induced SWNT flocculation in these nanocomposites. The electrical and mechanical properties of the SWNT/nylon nanocomposites are briefly discussed in terms of SWNT loading, dispersion, length and type of functionalization. (c) 2006 Elsevier Ltd. All rights reserved.