US citizens will need a valid passport, a visa, and certification for yellow fever vaccination prior to entering the Central African Republic.
As there is no website that you can refer to for any other information regarding visa requirements for this country, you may be able to get the most recent travel information from:
The Embassy of the Central African Republic
1618 22nd Street NW,
Washington, DC 20008
Telephone: (202) 483-7800 to 801