Connect a 8GB or larger USB key to your computer then launch the Mac App Store from your dock.
Navigate to the OS X Mavericks application page and click the Install button. If you are already on, or have already downloaded Mavericks, you may need to click the Download button.
Launch Disk Utility from the Applications:Utilities folder.
Select your USB thumb drive from the list on the left and click the Partition tab.
Set the Partition Layout to 1 Partition, set the Name to 'Mavericks', and set the Format to Mac OS Extended (Journaled).
Click the Options button then choose GUID Partition Table from the popup window then click the OK button.
Next click the Apply button to save your changes. When asked to confirm click the Partition button.
Launch Terminal from the Applications:Utilities folder.
Make sure your empty USB key is still inserted. Additionally, make sure you do not have any other volumes named 'Mavericks' except for the one we just created in Step Five.
Execute the following command in the Terminal window to create your OS X Mavericks Install key.
sudo '/Applications/Install OS X Mavericks.app/Contents/Resources/createinstallmedia' --volume '/Volumes/Mavericks' --applicationpath '/Applications/Install OS X Mavericks.app' --nointeraction
You will be asked to enter your Administrative account password.
After about 15 minutes the creation of your USB Install Key for OS X Mavericks will be complete.
You may now restart your Mac and hold down the Option key after hearing the boot sound. You'll be presented with a list of bootable drives. Select the USB install key.