Welcome to the Science China Chemistry special issue "Ionic Liquids and Green Chemistry".We have assembled 28 papers(13 from China and 15 from outside China)in the field to highlight the continued growth of this exciting area.We gratefully acknowledge the support from Science China Press and thank Prof.Xingmei Lu,Dr.Qian Wang,Dr.Guanqun Song,the authors,and the referees for their great contributions to this special issue.