The correct French styling of the word meaning a headwaiter, host, or waiter captain is maître d’hôtel. Preserve this spelling, with its two circumflexes, in written English. The word, which translates literally to master of the hotel takes the plural form maîtres d’hôtel, not maître d’hôtels, which would suggest a single master of multiple hotels rather than many masters (see plural compound nouns).
The phrasal noun is sometimes reduced to maître d’ (pronounced maître dee), though this should be treated as an informal colloquialism.