Abstract - Series of polystyrene/polyaniline core–shell composites were synthesized by adding reactive surfactant anilinium dodecylsulfate (DS−AN) as the monomer of polyaniline. DS−AN conversion to polyaniline was calculated by thermogravimetric analysis. Electron microscopy (high-resolution mode) showed that the conductive polymer was deposited over the polystyrene cores in the form of thin coatings. Composites electrical conductivity, determined by the 4−probe method, was in the range 10−6–10−2 S cm−1. The percolation−tunneling mechanism, according to the curve of conductivity (S cm−1) versus polyaniline (wt%), was the electron transfer mechanism. Finally, all the composites were electroactive, as shown by cyclic voltammetry.