Anyone done this as I am sure you have, can it be done in a one day visit to embassy. live in Hua Hin so a long trip. help me guys/

ps problem here need new pages in passport.

Make an appointment with the American Citizens Services online first.

It costs $82 (you can pay in Baht)

http://bangkok.usembassy.gov/extra_visa_pages.html

It can be done in one day, but you must make an appointment via the Embassy's website (American Citizen Services). And it is no longer free...

(oops, sbk beat me to it).

Two things:

1) Highly recommend making an early AM appointment, even if you have to come up from Hua Hin the night before. In my experience, waking up early definitely trumps waiting longer in the queue (even with an appointment) later in the day.

2) Make sure you ask for 48 pages if you travel frequently as the default is only 24 pages. Getting 48 won't cost extra (still $82) but will save you time and hassle down the road if you need lots of pages.

ACS info: http://bangkok.usembassy.gov/extra_visa_pages.html