The　sensitivity　of　temperature　on　the　decomposition/polymerisation　of　ground　granulated　blast-furnace　slag　(GGBS)　was　investigated　through　the　dissolution　experiments　at　high　water　to　solid　ratio　under　controlled　temperatures　(5,　20,　and　40　degrees　C).　The　aqueous　compositions　during　the　dissolution　in　neutral　and　alkali　media　were　determined　by　ICP-OES　(Inductively　coupled　plasma-optical　emission　spectrometry)　and　the　saturation　conditions　with　respect　to　the　possible　precipitations　were　estimated　by　thermodynamic　modelling.　The　depolymerisation　of　silicate　groups　and　the　chemically　combined　water　in　the　residual　GGBS　was　examined　by　FTIR/　SEM　(Fourier　Transform　Infrared　spectroscopy/Scanning　Electron　Microscopy)　and　TG　(Thermogravimetric)　analysis　respectively.　The　results　demonstrated　that　the　effect　of　temperature　on　the　dissolution　of　GGBS　is　more　pronounced　from　5　degrees　C　to　20　degrees　C　than　that　from　20　degrees　C　to　40　degrees　C.　The　extremely　low　temperature　(-　5　degrees　C)　restricts　the　hydration　of　GGBS　even　in　a　high　pH　environment.　The　temperature　does　not　affect　the　depolymerising　sequences　of　silicate　groups　in　GGBS　in　a　neutral　environment　but　changes　the　overall　dissolution　rate.　The　major　silicate　spices　(Q0　to　Q3)　in　GGBS　tend　to　dissolve　evenly　in　DI　water,　whereas　the　Q2　tends　to　depolymerise　faster　than　others　in　the　NaOH　solution.　The　decreasing　Ca　concentration　in　the　NaOH　solution　corresponds　to　the　formation　of　-　50　nm　needle-like　precipitates　regardless　of　temperature.　Based　on　the　results　collected,　the　dissolving　potential　and　the　temperature　sensitivity　of　the　major　components　in　GGBS　can　be　divided　into　three　batches:　the　easiest/most　sensitive　group:　Na-Ox;　intermediate　group:　K-Ox,　Si-Ox,　Ca-Ox,　Al-Ox;　the　hardest/　least　sensitive　group:　Mg-Ox.　The　intermediate　batch　required　an　initial　activation　energy　of　-　15　kJ/mol　in　DI　water.　The　relevant　data　could　be　considered　as　experimental　evidence　in　the　thermodynamic　modelling　of　the　hydration　of　GGBSs.