How To Make OSX Lion Bootable USB Flash Drive

Step 1: Download OS X Lion from the Mac App Store.

Step 2: Once downloaded, go to the Applications folder and find the copy of Lion you just downloaded.

Step 3: Right click on the downloaded file and select “Show Package Contents”.

Step 4: Go to “Contents” and jump inside the “SharedSupport” folder and you’ll find a file titled “InstallESD.dmg”. Copy this over to the desktop.

Step 5: Plug in a USB flash drive to your Mac having at least 4GB memory. We highly suggest going ahead with an 8GB one just to be on the safe side.

Step 5: Now open up “Disk Utility” and drag InstallESD.dmg from the desktop to the left-hand sidebar. Select the attached USB from left side and click on “Partition” tab.

Step 6: Select “1 Partition” from the Volume Scheme dropdown menu. Choose “Mac OS Extended (Journaled)” from the left.

Step 7: Now click on “Option” at the bottom. Select “GUID Partition Table” and press OK. Now click on Apply at the bottom right to start formatting.. (NOTE: This is will erase all data on your USB flash drive)

Step 8: Once the drive has been formatted, click on “Restore” (it’s right next to where you clicked on “Partition in Step 5).

Step 9: Choose USB drive you plugged-in in Step 5 as “Destination” with the InstallESD.dmg file as “Source”.

Step 10: Click Restore and type in your password. This will create the intended Lion bootable USB flash drive

Step 11: Reboot your Mac with the USB drive plugged in. Hold the “Option” key on your keyboard when you hear the iconic OS X startup chime. You can now boot into your Flash drive from there.

Step 12: Follow the on-screen instructions to install OS X Lion.

You may then follow Steps 11 and 12 to install Lion on all your Macs.