@Henrik ****
First answer with Google.
Yes, you must have a full, valid passport to enter Thailand. Foreign nationals are not permitted to use alternative identification documents, such as US driver's licenses or military IDs, for international travel or border entry.
Validity: Your passport must be valid for at least six months from your date of entry.
Visa Exemption: Most travelers (including US citizens) receive a 30–60 day visa exemption upon arrival, but this requires a compliant passport.
Exceptions: Only Thai citizens may enter with an expired Thai passport or national ID; all other foreigners require a valid passport.
Enforcement: Airlines will deny boarding if your passport does not meet the six-month validity rule, and Thai immigration will deny entry if it is not met.
Although yes the website would be the first place to go.