Sensor　networks　are　widely　used　in　environment　exploration　and　disaster　recovery　and　in　military　applications　due　to　their　self-organization　characteristics　and　distributed　nature.　As　a　fundamental　requirement　for　providing　security　functionality　in　sensor　networks,　key　management　plays　a　central　role　in　authentication　and　encryption.　In　this　paper,　we　present　a　hexagon-based　key　predistribution　scheme　and　show　that　it　can　improve　the　key　management　in　sensor　network　through　the　use　of　the　bivariate　polynomial　in　a　hexagonal　coordinate　system　based　on　deployment　information　about　expected　locations　of　the　sensor　nodes.　We　show　that　the　scheme　presented　here　can　improve　the　probability　of　establishing　pairwise　keys　between　sensor　nodes　of　up　to　two　hops　apart　by　more　than　40%　over　previous　schemes.　©　2006　IEEE.