All you neeed to know about Thai Baht
In Thailand, the local currency is the Thai Baht (THB). You can buy Thai Baht at exchange bureaus at the airport or in banks.

The BWI strongly recommends that you change your money at official exchange bureaus, as informal money changers are notoriously unreliable. Do not change money in hotels, where the exchange rate is
usually unfavourable.

The following major currencies are sure to be accepted for exchange: USD (United State Dollars), £ (British Pounds), € (Euros), CHF (Swiss Francs), ¥ (Japanese Yen) and MYR (Malaysian Ringgit).

Be careful when using your credit card, as cloning fraud is a major problem in Thailand.

Bring a minimum amount of USD 300.00 /€250.00 to cover:
Lunch, dinner, beverage and miscellaneous minimum) USD 200.00 and visa, airport tax, local, transport USD 100.00

For more details check BWI congress guide under Documents section.