Terpolymer resins (BPhUF) were synthesized by the condensation of 2,2'-dihydroxybiphenyl [BPh] and urea [U] with formaldehyde [F] in the presence of an acid catalyst and using varied molar ratios of reacting monomers. Terpolymer resin compositions have been determined on the basis of their elemental analysis and the number average molecular weights of these resins were determined by conductometric titration in nonaqueous medium. Visco- metric measurements in dimethyl formamide have been carried out with a view to ascertain the characteristic functions and constants. UV-VIS, IR, and NMR spectra were studied to elucidate the structure. (c) 2005 Wiley Periodicals, Inc.