A new dihydroxy monomer, 1-(2-hydroxypyridin-3-yl)-3-(2-(2-hydroxypyridin-3-yl)-1,3-dioxo-isoindoline-5-carbonyl)thiourea, with preformed trimellitic anhydride chloride-derived imide ring, pyridine and C=S moieties was synthesized. This compound was exploited to prepare three heteroaromatic poly(thiourea-imide-ester)s (PTIEs) by polycondensation with various diacid chlorides. Structural analysis of polymers was carried out by Fourier transformation infrared and nuclear magnetic resonance spectroscopy. PTIEs were readily soluble in polar solvents such as N, N-dimethylacetamide, dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone. Inherent viscosity and gel permeation chromatography measurements revealed high molar mass (140 × 10² to 101 × 10²). One of the polymers showed crystalline behavior according to x-ray diffraction. Thermogravimetric analysis and differential scanning calorimetry were adopted for the thermal analysis of the polymers. Novel aromatic PTIEs possess high weight loss temperature ( T₁₀) in the range 524–536°C and glass transition temperature of about 223–230°C.