Vinyl sulfonic acid (VSA) monomer at various pH values was polymerized by using a special radical initiator 2,2'-azobis(2-methylpropanediamine) dihydrochloride in 50 degrees C and 50 h by free radical polymerization method. The gravimetric conversions were obtained, and it was found that the conversion was the maximum in acidic media and the minimum in basic media. The structural behavior of poly(vinyl sulfonic acid) P(VSA) and poly(vinyl sulfonic acid sodium salt) P(VSANa) polymers were investigated by Fourier Transform Infrared (FT-IR), Raman, Nuclear Magnetic Resonance (NMR) (H-1, C-13, Distortionless Enhancement by Polarization Transfer ((DEPT)-D-135) and Homo Nuclear Correlation spectroscopy, (Cosy) and thermal properties were obtained by Thermal Gravimetry Analysis (TGA). It was found molecular weight approximately 6000 g/mol by H-1-NMR spectroscopy method for P(VSANa). Furthermore, for investigation of the microstructure of P(VSA) acid and P(VSANa), we used the Matrix-assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) spectroscopy method and Cosy NMR spectroscopy. The Microstructure for P(VSA) was found in cyclic form. The molecular weights for two homopolymers were obtained at 2300 g/m by MALDI-TOF spectroscopy.