The effect of the type of CNT (functionalized and non-functionalized) on the dielectric relaxation phenomena and conductivity of MWCNT/chitosan (MWCNT/CS) was investigated. Composites were prepared by the solvent cast method by homogeneously dispersing CNT into a CS matrix. FTIR analysis suggests the formation of hydrogen bonding in functionalized-MWCNT/CS whereas the CS remains unaffected in non-functionalized films. In the low conductivity region, the alpha-relaxation process associated with a glass transition in CS is affected by the MWCNT; the Vogel temperature increases due to a decrease of the water content. The sigma-relaxation exhibits a typical Arrhenius-type temperature dependence that is independent on the moisture content. Strong interfacial interactions of functionalized-MWCNT with the CS matrix are responsible for high values of the contact resistance R-c between individual CNT. Conversely, non-functionalized MWCNTs exhibit a typical 3D percolation threshold at ca. 4 wt %. (C) 2015 Elsevier B.V. All rights reserved.