How to install OS X Mountain Lion 10.8

by: Sean_W.

Last modified: Jul 3, 2021 11:16 PM

6 2442 Last modified Jul 3, 2021 11:16 PM

OS X Mountain Lion 10.8 is available for older systems that are not compatible with the latest version of macOS.

1. Check compatibility

Mac OS X Snow Leopard 10.6.8, Mac OS X Lion 10.7, or OS X Mountain Lion 10.8 already installed
2GB of memory
8GB of available storage space

You can install OS X Mountain Lion on any of these Macs. The latest supported software version is noted next to each model. See the Technical Specifications for the full list of requirements.

MacBook

Learn how to identify your MacBook.

MacBook (13-inch, Mid 2010) | 10.13.6
MacBook (13-inch, Late 2009) | 10.13.6
MacBook (13-inch, Mid 2009) | 10.11.6
MacBook (13-inch, Early 2009) | 10.11.6
MacBook (13-inch, Aluminum, Late 2008) | 10.11.6

MacBook Air

Learn how to identify your MacBook Air.

MacBook Air (13-inch, Mid 2013)* | Latest release of macOS
MacBook Air (11-inch, Mid 2013)* | Latest release of macOS
MacBook Air (13-inch, Mid 2012) | 10.15.7
MacBook Air (11-inch, Mid 2012) | 10.15.7
MacBook Air (13-inch, Mid 2011) | 10.13.6
MacBook Air (11-inch, Mid 2011) | 10.13.6
MacBook Air (13-inch, Late 2010) | 10.13.6
MacBook Air (11-inch, Late 2010) | 10.13.6
MacBook Air (Mid 2009) | 10.11.6
MacBook Air (Late 2008) | 10.11.6

MacBook Pro

Learn how to identify your MacBook Pro.

MacBook Pro (Retina, 15-inch, Early 2013) | 10.15.7
MacBook Pro (Retina, 13-inch, Early 2013) | 10.15.7
MacBook Pro (Retina, 13-inch, Late 2012) | 10.15.7
MacBook Pro (Retina, 15-inch, Mid 2012) | 10.15.7
MacBook Pro (15-inch, Mid 2012) | 10.15.7
MacBook Pro (13-inch, Mid 2012) | 10.15.7
MacBook Pro (17-inch, Late 2011) | 10.13.6
MacBook Pro (15-inch, Late 2011) | 10.13.6
MacBook Pro (13-inch, Late 2011) | 10.13.6
MacBook Pro (17-inch, Early 2011) | 10.13.6
MacBook Pro (15-inch, Early 2011) | 10.13.6
MacBook Pro (13-inch, Early 2011) | 10.13.6
MacBook Pro (17-inch, Mid 2010) | 10.13.6
MacBook Pro (15-inch, Mid 2010) | 10.13.6
MacBook Pro (13-inch, Mid 2010) | 10.13.6
MacBook Pro (17-inch, Mid 2009) | 10.11.6
MacBook Pro (15-inch, Mid 2009) | 10.11.6
MacBook Pro (15-inch, 2.53GHz, Mid 2009) | 10.11.6
MacBook Pro (13-inch, Mid 2009) | 10.11.6
MacBook Pro (17-inch, Early 2009) | 10.11.6
MacBook Pro (17-inch, Late 2008) | 10.11.6
MacBook Pro (15-inch, Late 2008) | 10.11.6
MacBook Pro (17-inch, Early 2008) | 10.11.6
MacBook Pro (15-inch, Early 2008) | 10.11.6
MacBook Pro (17-inch, 2.4 GHz) | 10.11.6
MacBook Pro (15-inch, 2.4/2.2GHz) | 10.11.6

iMac

Learn how to identify your iMac.

iMac (27-inch, Late 2013)* | 10.15.7
iMac (21.5-inch, Late 2013)* | 10.15.7
iMac (21.5-inch, Early 2013) | 10.15.7
iMac (27-inch, Late 2012) | 10.15.7
iMac (21.5-inch, Late 2012) | 10.15.7
iMac (21.5-inch, Late 2011) | 10.13.6
iMac (27-inch, Mid 2011) | 10.13.6
iMac (21.5-inch, Mid 2011) | 10.13.6
iMac (27-inch, Mid 2010) | 10.13.6
iMac (21.5-inch, Mid 2010) | 10.13.6
iMac (27-inch, Late 2009) | 10.13.6
iMac (21.5-inch, Late 2009) | 10.13.6
iMac (20-inch, Mid 2009) | 10.11.6
iMac (24-inch, Early 2009) | 10.11.6
iMac (20-inch, Early 2009) | 10.11.6
iMac (24-inch, Early 2008) | 10.11.6
iMac (20-inch, Early 2008) | 10.11.6
iMac (24-inch, Mid 2007) | 10.11.6
iMac (20-inch, Mid 2007) | 10.11.6

Mac Pro

Learn how to identify your Mac Pro.

Mac Pro (Mid 2012) | 10.14.6 with recommended Metal-capable graphics cards
Mac Pro (Mid 2010) | 10.14.6 with recommended Metal-capable graphics cards
Mac Pro (Early 2009) | 10.11.6
Mac Pro (Early 2008) | 10.11.6

Mac mini

Learn how to identify your Mac mini.

Mac mini (Late 2012)* | 10.15.7
Mac mini (Mid 2011) | 10.13.6
Mac mini (Mid 2010) | 10.13.6
Mac mini (Late 2009) | 10.11.6
Mac mini (Early 2009) | 10.11.6

* If your Mac shipped with OS X Mavericks 10.9 or later, it cannot be downgraded to OS X Mountain Lion 10.8.

2. Download and install OS X Mountain Lion

To upgrade from Mac OS X Tiger 10.4 or Mac OS X Leopard 10.5, first upgrade to Mac OS X Snow Leopard 10.6, then upgrade to OS X Mountain Lion 10.8. If you are unable to upgrade, see How to create a bootable installer for OS X Mountain Lion below.

To upgrade from Mac OS X Snow Leopard 10.6, download and install Mac OS X 10.6.8 Update Combo v1.1 followed by OS X Mountain Lion 10.8.5.

To upgrade from Mac OS X Lion 10.7, download and install OS X Mountain Lion 10.8.5.

Safari downloads the following installer as a disk image named InstallMacOSX.dmg. Open the disk image, then open the .pkg installer inside the disk image. It installs an app named Install OS X Mountain Lion. Open that app from your Applications folder to begin installing the operating system.

Please allow installation to complete without putting your Mac to sleep or closing its lid. During installation, it might restart and show a progress bar or blank screen several times. You might find it easiest to begin installation in the evening so that it can complete overnight, if needed.

OS X Mountain Lion 10.8 can upgrade Lion, Snow Leopard

3. Stay up to date

To get the latest features and maintain the security, stability, compatibility, and performance of your Mac, it's important to keep your software up to date. Apple recommends that you always use the latest macOS that is compatible with your Mac.

If your Mac isn't compatible with the latest macOS, you might still be able to upgrade to an earlier version, such as Catalina, Mojave, High Sierra, or El Capitan.

Helpful articles

How to create a bootable installer for OS X Mountain Lion

You can use an external drive or secondary volume as a startup disk from which to install the Mac operating system. These advanced steps are primarily for system administrators and others who are familiar with the command line.

What you need to create a bootable installer

A USB flash drive or other secondary volume formatted as Mac OS Extended, with at least 8GB of available storage
A downloaded installer for OS X Mountain Lion

Download OS X Mountain Lion

Download: OS X Mountain Lion
- This downloads as a disk image named InstallMacOSX.dmg. On a Mac that is compatible with Mountain Lion, open the disk image and run the installer within, named InstallMacOSX.pkg. It installs an app named Install OS X Mountain Lion into your Applications folder. You will create the bootable installer from this app, not from the disk image or .pkg installer.

Use the 'asr' command in Terminal

Connect the USB flash drive or other volume that you're using for the bootable installer.
Open Terminal, which is in the Utilities folder of your Applications folder.
Type or paste the following command in Terminal. This assumes that the installer is in your Applications folder, and MyVolume is the name of the USB flash drive or other volume you're using. If it has a different name, replace MyVolume in this command with the name of your volume.

Mountain Lion:

sudo asr restore --source /Applications/Install\ OS\ X\ \Mountain\ Lion.app/Contents/SharedSupport/InstallESD.dmg --target /Volumes/MyVolume --erase --noverify

After typing or pasting the command:

Press Return to enter the command.
When prompted, type your administrator password and press Return again. Terminal doesn't show any characters as you type your password.
When prompted, type Y to confirm that you want to erase the volume, then press Return. Terminal shows the progress as the volume is erased.
When Terminal says that it's done, you can quit the app and eject the volume.

Use the bootable installer

Plug the bootable installer into a compatible Mac that is connected to the internet.
Press and hold the Option (Alt) ⌥ key immediately after turning on or restarting your Mac.
Release the Option key when you see a screen showing your bootable volumes.
Select the volume containing the bootable installer. Then click the up arrow or press Return.
Choose your language, if prompted.
Select Install OS X from the Utilities window, then follow the onscreen instructions.

Learn more

Here are some additional resources that may be relevant.