We　demonstrate　herein　a　novel　solvent-free　technique　for　the　synthesis　of　sulfonic　acid　group-functionalized　mesoporous　organosilica,　which　was　achieved　from　the　self-assembly　of　a　block　copolymer　template　using　mercaptopropyltrimethoxysilane　(MPTS)　and　tetramethoxysilane　(TMOS)　under　melting　conditions　without　using　additional　solvents　and　subsequent　condensation　at　high　temperature　(up　to　140　°C).　The　resultant　samples　were　designated　as　SMS-xs,　where　x　stands　for　molar　ratio　of　MPTS/(MPTS　+　TMOS).　SMS-xs　have　relatively　large　BET　surface　areas,　highly　cross-linked　frameworks,　and　abundant　and　uniform　mesopores　with　wormhole-like　characteristics.　Interestingly,　MPTS　could　be　used　as　the　solo　precursor　to　prepare　mesoporous　organosilica　(SMS-1.0),　which　had　controllable　acidity　and　an　ultra-high　concentration　of　sulfur　(5.51　mmol　g　-1　,　the　highest　acid　density　to　date),　which　was　even　higher　than　those　of　commercial　Amberlyst　15　(4.7　mmol　g　-1　),　HS-JLU-20-0.8　(4.61　mmol　g　-1　)　and　sulfonated　carbon　(CH　0.30　O　0.33　S　0.16　,　4.90　mmol　g　-1　).　These　structural　characteristics　give　SMS-xs　excellent　activities　and　good　reusability　in　biomass　conversions　and　fine　chemicals　synthesis,　which　are　much　better　than　various　solid　acids,　such　as　Amberlyst　15,　H-form　USY　zeolite,　and　sulfonic　acid　group-functionalized　ordered　mesoporous　silica.　©　2018　The　Royal　Society　of　Chemistry.