Here are the Mac systems with which El Capitan is compatible: - iMac (Mid 2007 or newer)- MacBook Air (Late 2008 or newer)- MacBook (Late 2008 Aluminum, or Early 2009 or newer)- Mac mini (Early 2009 or newer)- MacBook Pro (Mid/Late 2007 or newer)- Mac Pro (Early 2008 or newer)- Xserve (Early 2009).