Composite materials of multi-walled carbon nanotubes (MWNTs) and a conducting polymer, poly(3-thiophene boronic acid) (PTBA) were prepared by in-situ oxidative polymerization of TBA in the presence of MWNTs and potassium dichromate. The MWNTs which were previously surface functionalized with acid chloride groups were reacted with TBA using a simple "chemical grafting" technique. It was observed that the nanotubes were dispersed uniformly in the pi-conjugated polymer matrix and entrapped by the polymer. The conductivity of the composites was higher than that of the pure polymer from a conventional four-probe technique, which indicates that the fabrication of MWNTs into the polymer matrix significantly improves the conductivity of the polymer due to the intrinsic properties of MWNTs.