beta-Naphthalene sulfonic acid (beta-NSA) has been electrochemically polymerized in a mixed electrolyte of boron trifluoride diethyl etherate (BFEE) solution mixed with a certain amount of trifluoroacetic acid (TFA) or concentrated sulfuric acid (SA). The poly(beta-naphthalene sulfonic acid) (PNSA) film prepared from the medium of BFEE+TFA was partly soluble in methanol. On the other hand, the polymer obtained from the system of BFEE+SA was soluble in water and general polar organic solvents such as methanol, alcohol, and acetone. The structure of PNSA was examined by infrared and UV spectra. Fluorescent spectral studies indicate that the polymer is a blue light emitter with fluorescence quantum efficiency of similar to 4%. (C) 2004 Wiley Periodicals, Inc.