Cellulose acetate (CA)-based nanocomposites with various contents of neat multiwalled carbon nanotube (MWCNT) or acid-treated one (MWCNT-COOH) are prepared via melt-compounding method and investigated their morphology, thermal stability, mechanical, and electrical properties. SEM microphotographs reveal that MWCNT-COOHs are dispersed uniformly in the CA matrix, compared with neat MWCNTs. FTIR spectra support that there exists a specific interaction between carboxyl groups of MWCNT-COOHs and ester groups of CA, indicating good interfacial adhesion between MWCNT-COOHs and CA matrix. Accordingly, thermal stability and dynamic mechanical properties of CA/MWCNT-COOH nanocomposites were higher than those of CA/MWCNT composites. On the contrary, electrical volume resistivities of CA/MWCNT-COOH nanocomposites are found to be somewhat higher than those of CA/MWCNT composites, which is because of the deterioration of graphene structures for MWCNT-COOHs and the good dispersion of MWCNT-COOHs in the CA matrix. (C) 2010 Wiley Periodicals, Inc. I Appl Polym Sci 118: 2475-2481, 2010