x86-64 processor (Macs with an Intel Core 2 Duo, Intel Core i3, Intel Core i5, Intel Core i7, or Xeon processor.) At least 2GB of RAM
Latest version of Mac OS X Snow Leopard (10.6.8), with the Mac App Store installed
At least 4GB of free disk space for downloading
Like Snow Leopard, Lion does not support PowerPC-based Macs (e.g., Power Macs, PowerBooks, iBooks, iMacs (G3-G5), eMacs).
Furthermore, Lion does not support 32-bit Intel Core Duo or Core Solo based Macs. Rosetta is no longer available in Lion, which means Lion no longer supports PowerPC applications.