He authored both a commentary on the Talmud as well as a collection of responsa, plus several other smaller works on focused topics. His father, Rav Sherira Gaon, was his teacher and predecessor as head of the academy. His students included Rabbeinu Chananel and Rav Nissim, the head of the academy at Kairouan.
External link
Hai Ben Sherira (http://www.jewishencyclopedia.com/view.jsp?artid=83&letter=H&search=Hai%20gaon), jewishencyclopedia.com