Urchin-like　Co　3　O　4　has　successfully　grown　directly　on　ITO　glass　and　sensor　ceramic　substrate　through　hydrothermal　reaction　followed　by　calcination.　The　combined　characterizations　of　X-ray　diffraction　(XRD)　patterns,　nitrogen　adsorption-desorption　and　scanning　electron　microscopy　(SEM)　indicate　that　the　as-prepared　product　possesses　good　crystallinity,　large　specific　surface　area　and　urchin-like　morphology　which　is　greatly　influenced　by　the　reaction　additives.　The　sensor　with　urchin-like　Co　3　O　4　growing　directly　on　ceramic　sensor　tube　exhibits　higher　response　sensitivity　than　the　sensors　fabricated　with　other　morphological　Co　3　O　4　or　by　traditional　coating　method.　©　2016　Elsevier　B.V.