Creating a bootable USB stick on OS X

Here’s a simple way to create a bootable USB stick from a downloaded .ISO file on OS X.

Convert ISO to IMG

Open the terminal and type the following command:

hdiutil convert -format UDRW -o target.img source.iso

Remember to replace the paths in the previous example.

Transfer to USB stick

Warning: This will erase all data on your USB stick.

First, find the correct device node:

diskutil list

After you have successfully identified your USB stick, unmount the disk (replace N with the disk number):

diskutil unmountDisk /dev/diskN

Finally, transfer the image to the USB stick (again, replace N with the disk number):

sudo dd if=target.img of=/dev/rdiskN bs=1m

After a short while, depending on the image size, your USB stick will be ready to use as a bootable media.

Source: http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-mac-osx