In　recent　years,　the　use　of　steel　tube　confined　concrete　(STCC)　columns　has　been　the　interests　of　many　structural　engineers.　The　present　study　is　an　attempt　to　study　the　monotonic　and　cyclic　behaviours　of　STCC　columns.　For　the　monotonic　behaviours,　a　series　of　tests　on　STCC　stub　columns　(twenty　one),　and　beam-columns　(twenty)　were　carried　out.　The　main　parameters　varied　in　the　tests　are:　(1)　column　section　types,　circular　and　square;　(2)　tube　diameter　(or　width)　to　thickness　ratio,　from　40　to　162,　and　(3)　load　eccentricity　ratio　(e/r),　from　0　to　0.5.　For　the　cyclic　behaviours,　the　test　parameters　included　the　sectional　types　and　the　axial　load　level　(n).　Twelve　STCC　column　specimens,　including　6　specimens　with　circular　sections　and　6　specimens　with　square　sections　were　tested　under　constant　axial　load　and　cyclically　increasing　flexural　loading.　Comparisons　are　made　with　predicted　column　strengths　and　flexural　stiffness　using　the　existing　codes.　It　was　found　that　STCC　columns　exhibit　very　high　levels　of　energy　dissipation　and　ductility,　particularly　when　subjected　to　high　axial　loads.　Generally,　the　energy　dissipation　ability　of　the　columns　with　circular　sections　was　much　higher　than　those　of　the　specimens　with　square　sections.　Comparisons　are　made　with　predicted　column　strengths　and　flexural　stiffness　using　the　existing　codes　such　as　AIJ-1997,　AISC-LRFD-1994,　BS5400-1979　and　EC4-1994.