Cobalt　nanowires　were　synthesized　by　reduction　of　carboxylate　salts　of　Co　in　1,　2-butanediol　using　a　solvothermal　chemical　process.　These　nanowires　crystallize　with　the　hcp　structure　and　the　growth　axis　is　parallel　to　the　crystallographic　c-axis.　The　morphology　of　the　nanowires　that　prepared　with　mechanical　stirring　during　earlier　stage　of　the　reaction　process　exhibits　a　smaller　averaged　aspect　ratio　but　narrow　size　distribution.　The　assembly　of　the　nanowires　that　prepared　with　mechanical　stirring　shows　almost　same　coercivity　and　remanent　magnetization　but　59%　increase　of　magnetic　energy　product.　This　remarkable　improvement　of　energy　product　has　been　further　understood　by　micromagnetic　simulations.　The　magnetic　performance　at　variant　temperatures　of　Co　nanowires　has　also　been　presented.　These　ferromagnetic　nanowires　could　be　new　ideal　building　blocks　for　permanent　magnets　with　high　performance　and　high　thermal　stability.　(C)　2018　Author(s).