Select the USB drive on the left menu, Erase tab.Plug your USB drive into your Mac and launch the Disk Utility application.Double-click InstallESD.dmg to open (or mount) it on your Desktop.Navigate to Contents > SharedSupport, then look for the filename 'InstallESD.dmg'.Look for the file called 'Install OS X Mountain Lion', Right-click and select Show Package Contents.Create bootable OS X Mountain LionĪfter your download is done, let’s proceed to making a bootable USB drive with your OS X Mountain Lion in it. Note: This may take up between 10 and 60 minutes, depending on the speed of your Internet connection. If you’ve previously purchased a copy of Mountain Lion, don’t worry, you will not be recharged.

Re-enter your App Store credentials if required.

Look for OS X Mountain Lion, hold down the Option key and click Download.

Launch the App Store and go to the Purchases tab.

Here’s how you can download and obtain a soft copy of Mountain Lion. The installer you downloaded from the App Store automatically deletes itself after you’ve successfully upgraded (or install) your Mac. Re-download Mountain Lion Installerįirst, grab hold of a copy of the Mountain Lion installer file. – I have confirmed this working on a Macbook Air 11″, 2010, 1.6Ghz version.While I was doing maintenance for my Mac, using the Maintenance app, the app told me that my.

– I would recommend creating a separate partition for your OS X Lion installation as well.

Hold Option/Alt after your see the Apple logo appear and boot with the thumbdrive in your Mac.Ĭhoose the USB Drive to install OS X Lion from your USB Thumbdrive! Once its finished, you now have a bootable OS X Lion install thumbdrive (basically just like what the Macbook Air ships with).ĥ. I recommend erasing the destination, so be sure to backup any data on the thumbdrive prior to this step! This will take a few minutes to do. (ie THUMBDRIVE in the screenshot) and then click Restore Once you have it chosen, click and drag your USB Thumbdrive from the left pane to the Destination box. Click on the Browse button and locate the. On the right pane, go to the Restore tab.ģ. This is very handy for us Macbook Air users that do not have an external optical drive.ġ. We can then boot the USB Drive on our Mac to install OS X Lion from it. dmg installer file for OS X Lion onto a usb thumbdrive.

– USB Thumbdrive or Memorycard Reader w/memory card (4GB mininum, data will be destroyed).

– Mac running OS X Leopard or Snow Leopard.

– OS X Lion installation DMG (hint: file named: mac_os_x_10_7_11a390.dmg).We will need a copy of the installer dmg (not provided) and a 4GB USB Thumbdrive or Memorycard Reader w/memory card and a Mac to convert the dmg to a bootable usb thumb drive. This recipe will explain how to make a USB Thumb Drive bootable with the OS X Lion Developer Preview installer on it and in turn allow you to install Lion on a Mac without an optical drive (ie Macbook Air line).

Create mac os lion bootable usb