The　exploitation　of　natural　gas　hydrates　(NGH)　via　CH4/CO2　exchange　is　promising　for　energy　extraction　and　carbon　sequestration,　while　the　presence　of　organic　matters　in　sediments　complicates　this　process.　In　this　study,　the　CH4/CO2　replacement　in　hydrate-bearing　muddy　silt　sediments　containing　organic　matters　was　investigated.　The　effects　of　organic　matter　type　(lignin,　humic　acid　(HA),　fulvic　acid　(FA))　and　content,　experimental　temperature　and　pressure,　saturations　of　initial　water　and　CH4　hydrate　were　systematically　examined.　The　results　revealed　that　organic　matter　significantly　improved　CH4/CO2　replacement.　For　the　1.0　wt%　HA-contained　sediments,　the　CH4　recovery　and　CO2　sequestration　rate　reached　51.07　%　and　30.66　%,　increasing　64.69　%　and　43.00　%　than　those　of　the　organic　matter-free　system,　respectively.　High　temperature　facilitated　CH4/CO2　swapping,　and　CO2　sequestration　rate　decreased　as　the　replacement　pressure　increased.　There　existed　an　optimal　initial　water　saturation　for　HA-contained　sediments　which　favored　CH4/CO2　replacement.　The　CH4　recovery　and　CO2　sequestration　rate　declined　with　the　increase　of　CH4　hydrate　saturation.　In　multi-stage　replacement,　CH4　recovery　continuously　increased　while　CO2　sequestration　rate　decreased　due　to　excess　CO2　injection.　The　CH4　recovery　achieved　73.12　%　after　the　third　stage　replacement,　increasing　around　17　%　compared　to　that　of　the　first　stage.　These　findings　contribute　to　better　understanding　CH4/CO2　replacement　in　practical　scenarios　and　offer　new　ideas　for　obtaining　CH4-rich　gas　in　gas　swapping　in　the　future.　©　2025　Elsevier　B.V.