Passport holders from Argentina, Brazil, Chile, Hong Kong, Laos, Macao, Mongolia, Peru, Russia and Vietnam can visit for 30 or 90 days.
Nationals from Cambodia and Myanmar can enter for 14 days without a visa.
The tourist visa exemption scheme allows visitors to enter for up to 30 days for Australia, Austria, Bahrain, Belgium, Brazil, Brunei, Canada, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hong Kong, Hungary, Iceland, Indonesia, Ireland, Israel, Italy, Japan, Kuwait, Latvia, Liechtenstein, Lithuania, Luxembourg, Malaysia, Maldives, Mauritius, Monaco, Netherlands, New Zealand, Norway, Oman, Peru, Philippines, Poland, Portugal, Qatar, San Marino, Singapore, Slovakia, Slovenia, South Africa, South Korea, Spain, Sweden, Switzerland, Turkey, Ukraine, United Arab Emirates, United Kingdom and United States.
A visa on arrival, valid for 15 days, is available for visitors from Bhutan, Bulgaria, China, Cyprus, Ethiopia, Fiji, Georgia, India, Kazakhstan, Malta, Mexico, Nauru, Papua New Guinea, Romania, Russia, Saudi Arabia, Taiwan, Uzbekistan and Vanuatu.
If you do need a visa, it is probably best to apply online.
Thailand visa information
Thailand visa on arrival
Thailand Ministry of Foreign Affairs
Thailand Embassies and Consulates