Poly(2-acetylamino-1,4-phenylene) was synthesized by coupling polymerization of 2,5-dibromoacetanilide. Partially hydrolyzed poly(2-acetylamino-1, 4-phenylene)s were prepared with a degree of hydrolysis per repeating unit from 15 to 98%. UV spectra and fluorescence were studied in DMSO and DMF/water solutions with varied acidity. The UV absorption maximum of poly(2-acetylamino 1,4-phenylene) is red-shifted from 255 to 285 nm with increasing degree of hydrolysis. At low degree of hydrolysis the emission spectra of polymers in DMSO/water solutions at different concentrations show that the emission km is almost independent of concentration. However, when the extent of hydrolysis increased, the emission bands were redshifted and became dependent of concentration. (c) 2007 Wiley Periodicals, Inc.