Polyimides having pendant; carboxyl groups were prepared by a direct one-pot polycondensation of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) with 3,5-diaminobenzoic acid (DABz) and bis[4-(3-aminophenoxy)phenyl]sulfone (m-BAPS) in the presence of a gamma -valerolactone/pyridine catalyst system using N-methyl-2-pyrrolidone (NMP)/toluene mixture asa solvent at 180 degreesC. The obtained polyimides were soluble in dipolar aprotic solvents such as dimethylformamide, dimethyl sulfoxide, and NMP as well as in tetrahydrofuran and aqueous basic solution. The solubility of the polyimides was dependent on the diamine composition. Photosensitve polyimide (PSPI) systems composed of the polyimides and diazonaphthoquinone compound as a photosensitive material gave positive-tone behavior by UV irradiation, followed by development with aqueous tetramethylammonium hydroxide (TMAH) solution. The scanning electron microscopic photograph of the resulting image showed 10-mum line/space resolution with about 15 mum of film thickness. The PSPIs baked at 350 degreesC for a short time had excellent thermal resistance comparable to the original polyimides. (C) 2001 John Wiley & Sons, Inc.