A　novel　hierarchical　porous　NiCo2O4　nanograss　array　directly　grown　on　Ni　foam　is　successfully　synthesized　through　a　facile　hydrothermal　method　combined　with　a　thermal　treatment.　When　used　as　the　electrode　material　for　supercapacitors,　an　areal　capacitance　of　2.1　F　cm(-2)　was　obtained　under　a　current　density　of　2　mA　cm(-2).　After　4000　charge-discharge　cycles,　a　high　areal　capacitance　retention　of　88%　could　be　achieved.　The　outstanding　electrochemical　performance　was　attributed　to　the　novel　structure　of　the　hierarchical　porous　NiCo2O4　nanograss　arrays　and　the　Ni　foam　used　as　the　current　collector.　The　novel　hierarchical　porous　NiCo(2)O4　nanograss　arrays　are　a　promising　electrode　material　for　supercapacitors.