Pure　and　Cobalt　doped　ZnO　microstructures　have　been　prepared　by　hydrothermal　method　and　calcinations　at　600　degrees　C.　The　crystal　structure,　surface　morphology　and　chemical　composition　of　the　samples　were　determined　by　X-ray　diffraction,　scanning　electron　microscopy　and　X-ray　photoelectron　spectroscopy,　respectively,　indicating　that　the　presence　of　a　small　quantity　of　Co　ions　can　greatly　affect　the　morphology　of　the　ZnO　nanostructures.　When　used　for　methane　gas　sensing,　1　wt%　Co/ZnO　(CZ(1))　sensor　exhibited　the　highest　response　to　100　ppm　methane　at　140　degrees　C,　which　were　about　2　times　higher　than　that　of　pure　ZnO　samples.　Moreover,　the　1　wt%　Co/ZnO　sensor　also　displayed　fast　response/recovery　time　(19/27　s),　low　detection　limit　(50　ppb).　Thus,　the　CZ(1)　microstructures　are　promising　for　practical　methane　sensing　applications.　(C)　2015　Elsevier　B.V.　All　rights　reserved.