Thermal　energy　storage　systems　(TES),　using　phase　change　material　(PCM)　in　building　walls,　has　become　a　hot　topic　within　the　research　community　in　recent　years.　As　more　and　more　articles　have　been　published,　it　is　essential　to　review　previous　work　so　as　to　have　a　good　knowledge　of　PCM　walls　in　energy　saving.　Several　aspects　are　discussed　in　this　review,　including　the　PCM　thermo-physical　properties,　PCM　types,　PCM　incorporation　methods　suitable　for　PCM　walls,　and　specific　application　methods　of　PCM　walls.　Although　it　is　known　theoretically　that　PCM　walls　have　a　relatively　good　potential　for　energy　saving,　more　researches　focusing　on　real　full-scale　buildings　and　real　operation　conditions　should　be　done　to　prove　the　authenticity　and　reliability　of　current　study.　(C)　2015　Published　by　Elsevier　Ltd.