Direct　interspecies　electron　transfer　(DIET)　between　electricigens　and　methanogens　has　been　shown　to　favour　CO2　reduction　to　produce　biomethane.　Furthermore,　DIET　is　accelerated　by　conductive　materials.　However,　whether　conductive　materials　can　promote　other　methanogenic　pathways　is　unclear　due　to　a　lack　of　detailed　experimental　data　and　the　poor　mechanistic　studies.　Here,　we　hypothesized　that　conductive　carbon　nanotubes　(CNTs)　stimulate　acetoclastic　methanogenesis　independently　of　electricigens　in　pure　cultures　of　Methanosarcina　spp.　and　anaerobic　wetland　soil.　We　found　a　significant　increase　in　the　methane　production　rate　during　the　growth　phase,　e.g.　from　0.169　mM　to　0.241　mM　after　addition　of　CNTs　on　the　3rd　day.　CNTs　did　not　increase　the　abundance　of　electromicroorganisms　or　the　electron　transfer　rate　in　anaerobic　soils,　using　via　microbial　diversity　and　electrochemical　analysis.　13C–CH3COOH　labelling,　stable　carbon　isotope　fractionation　and　the　CH3F　inhibitor　of　acetoclastic　methanogenesis　were　used　to　distinguish　methanogenic　pathways.　CNTs　mainly　accelerated　acetoclastic　methanogenesis　rather　than　CO2　reduction　in　both　pure　cultures　and　anaerobic　soils.　Furthermore,　the　presence　of　CNTs　slightly　alleviate　the　inhibition　of　CH3F　on　acetoclastic　methanogenesis　during　the　pure　culture　of　Methanosarcina　barkeri　and　Methanosarcina　mazei　with　the　production　of　more　than　0.3　mM　methane.　CNTs　closely　attached　to　the　cell　surface　were　observed　by　transmission　electron　microscopy.　Proteome　analysis　revealed　a　stimulation　of　protein　synthesis　with　about　twice　the　improvement　involved　in　–COOH　oxidation　and　electron　transfer.　Overall,　our　findings　demonstrate　that　conducting　CNTs　favor　methane　production　and　that　the　mechanism　involved　is　acetoclastic　methanogenesis　via　acetate　dismutation,　at　least　partly,　rather　than　classical　CO2　reduction.　©　2020　Elsevier　Ltd