In this study, polyindole (PIN) and polystyrene/polyindole (PS/PIN) composites were synthesized by chemical polymerization using FeCl3 as an oxidant agent. The conductivities of PIN and the composites were measured with a four-probe technique. The conductivity of PIN was determined as 5.1 x 10(-3) S cm(-1), whereas the conductivities of the PS/PIN composites were determined to 3.5 x 10(-4) and 2.4 x 10(-3) S cm(-1), respectively. From Gouy scale magnetic susceptibility measurements, it was found that PIN and the composites had polaron natures. In order to understand the electrical conduction mechanism of the composites Hall effect measurements of the composites were carried out in the temperature range of 170-350 K and under a magnetic field of 0.4 Tesla (T). Hall effect studies were used to investigate the nature, type and density of the charge carriers in conductive polymer composites. The transport properties are related to two physical quantities: the hall mobility and the carrier density. The mobilities of the investigated the composites decreased with increasing temperature, while the conductivity increased by the gradually increasing carrier densities. X-ray diffraction (XRD) analysis demonstrated the amorphous nature of PIN and its composites. The thermal properties of the samples were investigated by using thermogravimetric analyses (TGA) and found that they have good thermal stability. Morphological properties of the polymers, and composites have been investigated by scanning electron microscopy (SEM).