Wholly aromatic poly(azomethine)s with 1,5- or 2,6-substituted naphthalene moiety in the main chains were prepared in aprotic polar solvents or m-cresol under various reaction conditions. In the polymerization of 1,5-diaminonaphthalene with terephthalaldehyde, the polymer that synthesized in (HMPA/DMSO) at room temperature for 24 h by adding 5 wt % of calcium chloride and a very small amount of p-toluenesulfonic acid showed the highest reduced viscosity in all of the polymers from 1,5-diaminonaphthalene. The reduced viscosity of poly(azomethine)s synthesized from 2,6-diaminonaphthalene with 2,6-diformylnaphthalene in m-cresol and with terephthalaldehyde in HMPA/DMSO were eta(red) = 0.35 and 0.36, respectively. The thermal analysis showed the poly(azomethine)s had high thermal stability and the glass-transition temperatures of these polymers are about 250 degrees C. The X-ray diffraction showed that they are partially crystalline. They could be polymerized again by second stage polycondensation in polyphosphoric acid. The reduced viscosities of the obtained polymers were about 2-5 times as high as that of the pristine polymers.