The objective of this research was to investigate the effect of anions on the properties of soluble polyimides containing bipyridinium salt. Thus the work began with the synthesis of two new diamines: 1,1'-di[4-(4-aminophenoxy) phenyl]-4,4'-(1,4-phenylene)bis(2,6-diphenyl pyridinium dihydrogen phosphate) and 1,1'-di[4- (4-aminophenoxy)phenyl] -4,4'-(1,4-phenylene)bis(2,6-diphenyl pyridinium p-toluene-sulfonate). The two new diamines were polymerized with several dianhydrides to afford two new series of soluble polyimides. The polyimides have inherent viscosities that range from 0.284 to 0.449 dl g(-1) in N,N-dimethylformamide at 25 degrees C. These new polymers are soluble in polar aprotic solvents. Polymers containing H2PO4- show no glass transition temperature (T-g) and the T(g)s of polymers containing p-toluenesulfonate (PTS-) are around 240 degrees C. Thermogravimetric analysis showed that the polymers began to decompose in the range from 390 to 419 degrees C. Studies showed that the solubility, T(g)s, thermal stabilities, absorption in the visible region and photosensitivities of the polymers were affected by the basicity, structure, thermal stabilities and soft/hard character of the anions, respectively.