<p>This is a study on the influence of medium pH on the protonation degree and solubility of chitosan (CS). Results indicate that CS fully dissolves at a pH of 6, corresponding to a protonation degree of approximately 70%. We also determined that CS at this protonation level did not form complexes with silver ions (Ag⁺) in aqueous solutions, preventing the use of CS–Ag⁺ complexes as precursors for synthesizing nanoscale silver iodide (AgI) particles. The optimal concentrations of chitosan and the dispersed phase, as well as the ratio of AgNO₃ and KI, were determined to obtain stable positive and negative dispersion of AgI particles. Calculations of the lengths of the Kuhn segments of chitosan and polyethylenimine macromolecules at pH 3 are given. AgI particles were synthesized using two methods, involving an excess of either Ag⁺ or I⁻ ions, in aqueous solutions of polyethylenimine (PEI) and CS. Transmission spectroscopy revealed that, regardless of the synthesis method, particles formed in the presence of CS were larger and exhibit a broader size distribution compared to those formed with PEI. Additionally, we found that irrespective of the polymer used, particles synthesized with an excess of Ag⁺ ions were smaller than those produced with an excess of I⁻ ions.</p> Graphical Abstract <p></p>