Two hemicyanine dyes, trans-4-[p-(N,N-di(2-hydroxyethyl)) amino-styryl]-N-methylpyridinium tetraphenylborate (dye-C-1) and trans-4-[p-(N,N-di(2-hydroxyethyl)) amino-styryl]-N-octylpyridinium tetraphenylborate (dye-C-8) were synthesized, and characterized by infrared, H-1-NMR, thermoanalysis, respectively. Then polyimide (PI) oligomers (referred to as P-C-1 and P-C-8) with these hemicyanine dyes attached to the polymer side chain were prepared through Mitsunobu condensation. When the linear optical properties of the two dyes and the two PI oligomers were studied in dimethylformamide solvent, there were obvious blue shifts in the spectra of the oligomers. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 113: 1448-1453, 2009