Highly　porous　Si3N4　ceramics　have　been　prepared　via　a　novel　carbothermal　reduction-nitridation　(CRN)　reaction　between　carbon　nanotubes　(CNTs)　and　SiO　vapor　in　a　N2　atmosphere.　The　green　bodies　consisted　of　49.0　wt%　CNT,　40.4　wt%　α-Si3N4　as　seed　and　10.6　wt%　Y2O3　as　sintering　additive,　and　SiO　powders　were　located　under　the　green　bodies　during　sintering.　By　heating　at　temperatures　ranging　from　1550　to　1650　°C,　fibrous　β-Si3N4　nanograins　were　obtained.　Complete　reaction　was　achieved　after　soaking　at　1650　°C,　and　a　mean　grain　diameter　of　approximately　290　nm　and　aspect　ratio　of　as　high　as　20　were　obtained,　and　a　porosity　of　73%　was　reached　due　to　the　low　density　of　the　green　bodies.　The　bending　and　compressive　strengths　were　up　to　62　MPa　and　82　MPa,　respectively,　which　were　higher　than　the　values　in　the　literature,　as　a　result　of　the　fine　elongated　fibrous　β-Si3N4　grains.　It　should　be　noted　that　the　Si3N4　ceramics　exhibited　a　large　strain　to　failure　and　‘pseudoplastic’　deformation　behavior　during　the　compressive　test,　which　was　attributed　to　the　high　porosity.　©　2019　Elsevier　Ltd　and　Techna　Group　S.r.l.