Nanocomposites of conducting polyaniline with various transition metals have been synthesized via in situ by oxidizing the complex of aniline. The effect of CdS-nanoparticles on the electrical conductivity of polyaniline was discussed. The as prepared products were characterized by FT-IR and Transmission electron Microscopy. Different nanocomposites were compared with CdS-polyaniline nanocomposites. FTIR absorption band at 3600 - 3500 cm-1 confirmed the highly attached polyaniline with CdS nanoparticles. TEM showed the CdS particles are spherical with the average diameter of 19 nm which was evenly distributed in polymer matrix. The uniform intercalation of CdS nanoparticles results in a cooperative phenomenon between the polyaniline and the nanoparticles, as a consequence, the CdS nanoparticles increased the electrical conductivity of polyaniline nanocomposite to 6.50x10-2 S/cm compared to the pure polyaniline (10-10 S/cm); Germanium (10-2 S/cm) and Silicon (10-4S/cm) semiconductors. Its electrical conductivity was found to be analogous with existing semiconducting metals. The fact is supported by the ample of experimental results and characterization evidences.