Polypropylene (PP)/functionalized multiwalled carbon nanotube (F-MWNT) nanocomposites were prepared by using solution intercalation method with different F-MWNT loads. The PP composite films, which contain dodecanol-MWNT (DDO-MWNT) or dodecylamine-MWNT (DDA-MWNT) as reinforcing additive, were evaluated by thermomechanical properties, morphology, electrical conductivity and gas permeability. The images from electron microscopy (SEM and TEM) showed that F-MWNTs were homogeneously dispersed in PP matrix, while they were agglomerated in some other part. The addition of F-MWNT could improve thermomechanical properties of the films. The maximum enhancement was observed at 2 wt% F-MWNT. DDO-MWNT was more effective than DDA-MWNT for both tensile modulus and optical transparency of the films.