Novel carbon nanofiber (CNF) -filled bis-malemide composites were fabricated by a thermokinetic mixing method. The thermal and mechanical properties of composites containing 1 wt % and 2 wt CNFs were investigated. Thermogravimetric analysis demonstrated that minimal improvement in thermal stability of the nanocomposites was obtained by the addition of CNFs. Dynamic mechanical analysis showed an increase in storage modulus (E') and glass transition temperature (T-g) upon incorporation of nanofibers. Limiting oxygen index (LOI) has also been found to increase with incorporation of CNFs. Morphological studies of fractured surfaces of the composites has been carried out by scanning electron microscopy to determine the effect of fiber content and dispersion on the failure mechanism. In general, good dispersion was observed, along with agglomeration at some points and some fiber matrix interfacial debonding. A decrease in mechanical strength has been observed and debonding was found as the main failure mechanism. Further research outlook is also presented. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2159-2167, 2010