The conformational modification of model peptide (lysozyme), which was solubilized in various concentrations of aqueous-ethanolic solutions (0-99% v/v), were characterized by circular dichroism and fluorometry. It was found that at 80% v/v ethanol, lysozyme changed its conformation to molten globule (MG) state. After HCl was introduced to achieve a solution of pH~2, only 35% v/v ethanol was required in order to initiate MG state. However, MG state was not generated when acidic solution was used alone without ethanol. This conformational change from native state to MG state was found to be reversible by simple aqueous dilution.