A multiwalled carbon nanotube (c-MWNT)/polyaniline (PANI) composite was synthesized by an in situ chemical oxidative polymerization process. With the carbon nanotube loading increased from 0 to 30 wt %,, the conductivity also increased and became weakly temperature-dependent. Fourier transform infrared spectroscopy studies showed that the synthesis by an in situ process led to effective site-selective interactions between the quinoid ring of the PANI and the multiwalled nanotubes, facilitating charge-transfer processes between the two components. The morphological analysis indicated that the c-MWNTs were well dispersed and isolated, and the tubes became crowded proportionally to the weight percentage of c-MWNTs used in the composites. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 680-684, 2009