Polyamides were prepared from 2, 5-dibromoterephthalic acid (TBr2) with hexamethylenediamine, piperadine, p-phenylenediamine or 4, 4′-diaminodiphenylether. Polyesters were also prepared from TBr2 with bisphenol-A or ethylene glycol. Synthesis and properties of these polymers were compared with homologous polymers prepared from terephthalic acid (T) or 2, 5-dichloroterephthalic acid (TCl2) in order to investigate the effect of halogen substitution.ηsp/C decreased in the order for polymers from T>TCl2>TBr2 by low temperature solution polymerization, and T>TBr2>TCl2 by interfacial polymerization. Melting point decreased in the order for polyamides from T>TBr2>TCl2, and polyesters from T>TCl2>TBr2. TG curves of polymers from TBr2 showed lower decomposition temperature and higher residue than those of polymers from T or TCl2. Self-ignition temperature increased remarkably by halogen substitution especially for polyamides, and polymers from TBr2 showed longer ignition lag than polymers from TCl2. Polyesters from TBr2 had better solubility to organic solvents than polyesters from TCl2.