Americans who plan to visit Comoros need a valid US passport and visa to do so. You can either obtain a visa from the Comoran Mission to the United Nations in New York, or upon entry. A fee of 60 Euros will have to be paid for the visa.
Since there are no embassies or consulates for Comoros in the United States, please direct your inquiries regarding visas to:
The Mission of the Union of Comoros