The　influence　of　formation　potential　on　the　electrochemical　behaviour　and　passive　film　properties　of　Cu-28.6Sn　bronze　in　simulated　archaeological　soil　solutions　was　evaluated　using　combined　potentiodynamic　electrochemical　measurements,　electrochemical　impedance　spectroscopy,　and　the　Mott–Schottky　(MS)　approach,　with　ex　situ　surface　analytical　techniques　such　as　X-ray　photoelectron　spectroscopy.　Passive　films　were　formed　in　sodium　chloride　(NaCl)　solution　and　a　mixture　of　NaCl　and　sodium　sulphate　and　their　stability　increased　as　the　applied　potential　increased.　The　MS　measurements　indicated　that　a　very　thin　p-　and　n-type　porous　passive　film　was　formed　on　the　bronze　in　the　NaCl　and　sodium　sulphate　solution.　The　calculated　donor　density　decreased　exponentially　with　increasing　passive　film　formation　potentials　in　the　NaCl　solution　and　in　the　NaCl　and　sodium　sulphate　mixture.　Based　on　the　evaluations　of　the　surface　compositional　analysis,　the　primary　constituents　of　the　films　are　Cu　and　Sn;　in　addition,　dehydration　of　films　was　noted.　©　2020　Wiley-VCH　GmbH