Schiff's base monomers oi 12 different structures end-capped with terminal phenylacetylene groups have been synthesized by the reactions of o-, m-, p-phenyl ethynylbenzaldehyde (PEBA) and 4,4'-methylenedianiline (p-MDA), p-aminophenylether (P-APE), p-aminophenylsulfone (p-APS), and p-aminophenyldisulfide (p-APDS). The first-stage thermal polymerization was carried out at a melting point of each monomer in an air environment. Since the monomers are changed to viscous liquid during the first-stage polymerization, they could be fabricated and solidified into moldings, castings, and prepregs. The processing temperature range was varied to a great extent with the monomer structure. The second-stage polymerization was carried out with the polymers from the first-stage polymerization by Increasing the temperature to 800 ℃ in an inert environment. On this heat treatment, the polymers became electroconductive showing a bulk conductivity of 10^-1∼10^-3 S/cm. Monomers synthesized by o-PEBA could not form the conjugated three-dimensional matrix due to the thermal decomposition during polymerization. These conductive polymers did not lose their conductivities even after exposure to an air environment.