Step 1 :- Go to this page and download the latest USB version of Chrome OS.
Step 2 :- Click here and download Win32DiskImager.
Step 3 :- Extract both of the downloaded files as both the files are in compressed form.
Step 4 :- Plug in the USB flash drive which you wish to make Chrome OS bootable USB stick but make sure that it’s at least 4 GB in size and blank.
Step 5 :- Open Win32DiskImager.
Step 6 :- Browse to and mount your Chrome OS image in the “Image File” column in Win32DiskImager.
Step 7 :- Mount the USB stick by selecting it’s drive letter in the “Device” drop down menu in Win32DiskImager.
Step 8 :- Click on “Write” button in Win32DiskImager to burn the Chrome OS image to the USB drive you selected.
Practical demonstration of the above steps :-