A model compound was obtained by reaction of benzoic acid and 4,6-diamino-1,3-dihydroxybenzene dihydrochloride (DADHB center dot 2HCl) in the presence of functionalized multiwall carbon nanotubes (FMWNTs). FMWNTs were formed on raw multiwall carbon nanotubes (MWNTs) by chemical modification. The model compound was rinsed by chloroform and MWNTs were separated by centrifuge. The sediment yielded was denoted as graft multiwall carbon nanotubes (GMWNTs). Then X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier-transform infrared (FTIR) were used to investigate the existence of covalent bond between DADHB and FMWNTs. The results of XPS showed that nitrogen atoms amounted to about 3.3% except for oxygen and carbon on the surface of GMWNTs. Meantime, the reaction of -COOH of the FMWNTs and the monomer DADHB occurred, and benzoxazole was formed predominantly by Raman spectroscopy analysis. FTIR spectroscopy confirmed the covalent grafting of monomer to FMWNTs in the processing procedure. As a result, the mechanism of the reaction of the poly(p-phenylenebenzoxazole) (PBO) oligomer and FMWNT composites was deduced according to the reaction of the model compound. (C) 2007 Wiley Periodicals, Inc.