Access Keys:
Skip to content (Access Key - 0)

Upgrade to OS X Mountain Lion (10.8)

Note: As with all operating system upgrades, please ensure you have completed a full backup of your system (using a service such as CrashPlan PROe) before beginning.
Note: Make sure that FileVault 2 is disabled on your on your machine, since this can cause problems with the upgrade after a restart.
Note: OS X Mountain (10.8) is no longer available via the Software Grid, users will have to download a copy through another source.


  • OS X 10.6.8 (Snow Leopard) or later
  • 8 GB of available disk space
  • 2 GB of RAM
  • Administrator account access

Supported models:

  • iMac (Mid 2007 or newer)
  • MacBook (Late 2008 Aluminum, or Early 2009 or newer)
  • MacBook Pro (Mid/Late 2007 or newer)
  • Xserve (Early 2009)
  • MacBook Air (Late 2008 or newer)
  • Mac mini (Early 2009 or newer)
  • Mac Pro (Early 2008 or newer)


Installation can take 40 minutes or more to complete
  1. Once you've downloaded OS X 10.8 for installation, find and double-click the downloaded disk image file.
    Result: The file will verify, then open.
    Install Mountain Lion disk image icon

    opening installation disk image screen

  2. Double-click the application labeled Install OS X Mountain Lion.
    installation application icon

  3. From the window labeled Install OS X select the button labeled Continue.
    install OS X first screen

  4. When presented with the license agreement, click Agree.
    license agreement screen

  5. Click Agree again from the slide-down screen.
    accept the agreement screen

  6. Select a drive to install OS X Mountain Lion on (if you only have one disk available on your Mac, you don't have to select anything) and click Install.
    select a drive screen

  7. Enter the username and password for your user account when prompted and select OK.
    username and password prompt

  8. The application will now download the installation files.
    installing progress screen

  9. Once these files have been downloaded, you can either click Restart to restart your Mac or it will restart automatically after a set period of time.
    ready to restart screen

  10. Upon restart, OS X Mountain Lion will begin installing. You cannot use your computer during this time.
    installing progress screen after restart

  11. When the installation has completed, your computer will automatically restart.
    Result: OS X Mountain Lion (10.8) has been successfully installed.

To learn what's new in OS X Mountain Lion, visit Apple's Mountain Lion page.

For additional Mountain Lion documentation, visit the Mountain Lion landing page in the Knowledge Base.

IS&T Contributions

Documentation and information provided by IS&T staff members

Last Modified:

April 27, 2016

Get Help

Request help
from the Help Desk
Report a security incident
to the Security Team
upgrade upgrade Delete
install install Delete
108 108 Delete
mountain mountain Delete
lion lion Delete
apple apple Delete
mac mac Delete
os os Delete
x x Delete
update update Delete
installation installation Delete
download download Delete
software software Delete
c-macos-mountain-lion c-macos-mountain-lion Delete
sccleanup sccleanup Delete
Enter labels to add to this page:
Please wait 
Looking for a label? Just start typing.
This product/service is:
Easy to use
Difficult to use

This article is:
Adaptavist Theme Builder (4.2.3) Powered by Atlassian Confluence 3.5.13, the Enterprise Wiki