Cellulose nanofibers (CNFs) from oil palm empty fruit bunches were chemically modified by acetylation with acetic anhydride and pyridine (as the solvent and catalyst). The acetylated CNFs showed good dispersion in a polychloroprene (PCR) matrix. The tensile strength and modulus of neat PCR were improved, whereas its elongation at break decreased with increasing nanofiber content. Above the glass-transition temperature (Tg), the dynamic mechanical analysis profiles showed that the storage modulus of the PCR–cellulose nanocomposites was higher than that of neat PCR. Meanwhile, the thermal stability was still maintained, and the Tg was close to the neat PCR at the 5 wt % addition level of CNFs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40159.