A new diol with a one-sided azobenzene-carboxyl group was prepared to be used for photosensible polymers synthesis. Azobenzene carboxyl containing polyurethane based on poly(tetramethylene oxide) diol of 2000 average molecular weight, 2,4-tolylene diisocyanate, and the mentioned azo diol, was obtained and characterized. Upon neutralization the acid form with metal acetate (Li+1, Ca+2) or triethylamine azo carboxylate anionomers with an improved phase separation were obtained. Viscometric measurements of diluted dimethylformamide solutions exhibited evidence of polyelectrolyte behavior. Some aspects of the trans-cis photoisomerization have been examined to design in future various dyed aqueous dispersions. (C) 2005 Wiley Periodicals, Inc.