Anisotropic polymerization of 5-hydroxy isophthalic acid and isophthalic acid with 2,5-diamino 1,4-benzene dithiol dihydrochloride (DABDT.2 HCl) affords the polymer poly {[benzo (1,2-d: 4,5-d’) bisthiazole-2, 6 diyl]-1,3 phenylene} and poly {[benzo (1,2-d: 4,5-d’) bisthiazole-2, 6 diyl]-1,3(5-hydroxy phenylene)}. Both the polymers were soluble in methanesulphonic acid and chlorosulphonic acid. The polybenzobisthiazoles do not show any glass transition temperature (Tg) by DSC analysis. The polybenzobisthiazoles were stable up to 400oC in a nitrogen environment, according to thermo gravimetric measurements. Elemental analysis and spectroscopic comparison of the polymers with the appropriate model compounds were used to confirm the polymer structures. The polymers' inherent viscosity reached 4.2 dL/g (methanesulphonic acid, 30oC).