In　this　study,　we　examined　the　cyclic　stability　of　Prussian　blue　(PB)　films　in　electrolytes　with　acid.　The　cyclic　stabilities　of　the　PB　films　were　investigated　in　K+　based　electrolytes　with　different　values　of　solution　pH.　The　acidified　KCl　solution　can　significantly　improve　the　durability　of　the　film.　Among　the　three　pH　values　tested,　the　KCl　solutions　(pH　=　2.15　and　pH　=　3.03)　showed　better　performance.　Furthermore,　we　investigated　the　cyclic　stabilities　of　the　PB　films　in　LiClO4/PC　electrolyte　containing　different　acids.　We　found　that　the　cyclic　stability　of　PB　film　was　significantly　improved　when　a　small　amount　of　acetic　acid　was　dissolved　in　LiClO4/PC　electrolyte.　The　PB　film　exhibited　stable　optical　modulation　after　up　to　20,000　cycles　in　LiClO4/PC　electrolyte　containing　acetic　acid-a　much　higher　result　than　those　of　some　literatures.　This　suggests　that　the　addition　of　acetic　acid　to　LiClO4/PC　electrolyte　can　promote　the　development　of　PB-based　devices　with　improved　stability.