<p>The aim of this research is the identification of the changes in anion- and solvent-dependent polaronic transitions and the ratio of acid to monomer during the polymerization of new poly(<i>ortho</i>-methoxyaniline) nanosilica-supported sulfuric acid emeraldine salt1/salt2 (POMA-NSSSA-ES1/ES2) nanocomposites. The synthesis is done by doping poly(<i>ortho</i>-methoxyaniline)-emeraldine base (POMA-EB) in the presence of nanosilica-supported sulfuric acid (NSSSA) under solid-state condition. The structure, size, and morphology of all samples were identified using spectroscopy methods. Effect of acid concentration (0.5, 1.5, and 2.0) and low- and high-valent sulfate anion (H₂SO₄/HSO₄⁻ Vs. HSO₄⁻/SO₄²⁻) on polaronic transitions of poly(<i>ortho</i>-methoxyaniline) nanocomposites in different solvents (NMP, MCR, DMSO, and MeOH), and conductivity were studied. Afterwards, changes in polaron mutations under changing conditions were analyzed. Increasing the acid concentration compared to the monomer increases the absorption number (λ_max) in the UV–Vis study along with hypsochromic effect (blueshift) and bathochromic effect (redshift) in low acid concentration for polaronic transition. The anion effect proved that by increasing the negative charge of the anion (SO₄²⁻) due to the limiting potential of the polaron and bipolaron structures, it prevents the creation of delocalized polaron structure with no change in the POMA-NSSSA-ES2 nanocomposite conductivity. Results showed that the average size of nanocomposite particle obtained by this method was a range of 40–50 nm and the morphology of nanocomposites was spherical (nanospheres). POMA-NSSSA nanocomposites were completely in a doped state and the emeraldine salt from of POMA. During this research, for the first time, the polaronic orbital energy level was determined.</p> Graphical abstract <p></p>