Electrically semiconducting polypyrrole/multi-walled carbon nanotube (PPy/MWNTs) composites were prepared by in-situ oxidative polymerization of pyrrole in the presence of MWNTs in supercritical carbon dioxide (scCO(2)). Prior to the polymerization, MWNTs were surface modified with silane coupling agent 3-(trimethoxysilyl) propyl methacrylate in order to be dispersed well in scCO(2). TEM and FESEM analysis showed that a tubular layer of PPy film is coated on the MWNTs surfaces, which were a few nanometers in thickness. The incorporation of MWNTs in the composite was endorsed by FT-IR. The composites were also confirmed by XRD and XPS. The composites synthesized in scCO(2) were shown to possess higher thermal stability and electrical conductivity than PPy. Additionally, the dispersibility of the composite in ethanol was also demonstrated.