Magnetic　properties　and　thermal　stability　were　investigated　for　the　MnBi/NdFeB　(MnBi　-　0,　20,　40,　60,　80,　and　100　wt.%)　bonded　hybrid　magnets　prepared　by　spark　plasma　sintering　(SPS)　technique.　Effect　of　MnBi　content　on　the　magnetic　properties　of　the　hybrid　magnets　was　studied.　With　increasing　MnBi　content,　the　coercivity　of　the　MnBi/NdFeB　hybrid　magnets　increases　rapidly,　while　the　remanence　and　maximum　energy　product　drops　simultaneously.　Thermal　stability　measurement　on　MnBi　magnet,　NdFeB　magnet,　and　the　hybrid　magnet　with　20　wt.%　MnBi　indicates　that　both　the　NdFeB　magnet　and　the　MnBi/NdFeB　hybrid　magnet　have　a　negative　temperature　coefficient　of　coercivity,　while　the　MnBi　magnet　has　a　positive　one.　The　(BH)(max)　of　the　MnBi/NdFeB　magnet　(MnBi　-　20　wt.%)　is　5.71　MGOe　at　423　K,　which　is　much　higher　than　3.67　MGOe　of　the　NdFeB　magnet,　indicating　a　remarkable　improvement　of　thermal　stability.　(c)　2011　American　Institute　of　Physics.　[doi:10.1063/1.3564966]