A series of new poly(1,2,4-triazole)s (PTAs) containing pyridine heterocyclic ring, bearing bulky aromatic pendent groups, were synthesized from the reaction of the corresponding polyhydrazides with aniline or 4-aminobenzenesulfonic acid in polyphosphoric acid (PPA) at 175 A degrees C. The non-sulfonated PTAs showed glass transition temperatures (T (g)s) of 220-250 A degrees C and inherent viscosities (eta (inh)) equal to 0.48-0.78 dL/g, and the sulfonated poly(1,2,4-triazole)s (S-PTAs) exhibited T (g)s of 235-265 A degrees C and inherent viscosities equal to 0.50-0.83 dL/g. The former polymers were soluble in conc. H2SO4 and partially soluble in hot N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), and 1-methyl-2-pyrrolidone (NMP), and the latter were soluble in DMF, NMP, DMSO and DMAc at room temperature. All polymers had useful levels of thermal stability and were stable up to 450 A degrees C in nitrogen. The proton conductivities of undoped sulfonated polytriazole membranes and the acid-doped sulfonated polytriazole membranes lie in the range of 5 x 10(-4)-8.1 x 10(-3) and 5 x 10(-3)-2.3 x 10(-2) S/cm, respectively, at 90 A degrees C and 100 % relative humidity.