In this research, polystyrene/polypyrrole composite was developed by firstly carrying out the emulsion polymerization of styrene to obtain polystyrene as a fine powder. Then polypyrrole was synthesized by chemical oxidation method in the presence of polystyrene particle using FeCl2 as the oxidant. The composite appeared as black particle, which was polypyrrole, covered on polystyrene and was analyzed by Attenuated Total Reflectance (ATR) FT-IR spectroscopy. Several factors, i.e. pyrrole volume, reaction time, reaction temperature, and solvent were investigated to optimize the reaction condition for achieving the highest conductivity of this composite. The other host polymers were attempted including poly(vinyl chloride), polyethylene, and polypropylene. The results indicated that polystyrene/polypyrrole and poly(vinyl chloride)/polypyrrole composite could have the conductivity as high as 10 Scm' which was the highest conductivity for this type of composites ever been reported. The time decay of conductivity of some polypyrrole composite was also explored.