http://www.thai-consulate.org.hk/internet/attachments/607.pdf

1. A copy of Hong Kong/Macau resident I.D. card.
2. Passport/Travel document (original) with a copy of the photo page.
3. Passport of at least 6 months validity and two clear pages for a visa sticker.
4. One application form must be completely filled out in English. (CAPITAL LETTER)
5. One recent photo with 1.5x2 inches in size, with clear face taken within last 6 months.

http://www.thai-consulate.org.hk/web/3015.php?s=4101