"Whereas the name Jehovah appears in the King James Version and other Bible translations, some prefer to use the name Yahweh instead of Jehovah. Which name is correct?
"The most ancient Bible manuscripts were written in the Hebrew language. In the Hebrew Scriptures, the divine name occurs almost 7,000 times and is spelled with four consonants—YHWH or JHVH. These four-consonant words are commonly called the Tetragrammaton, or Tetragram, derived from two Greek words meaning "four letters." Now the question of accurate pronunciation arises because early Hebrew writing consisted of consonants with no vowels to guide the reader. So whether the pronunciation of the Tetragrammaton becomes Yahweh or Jehovah depends on which vowels the reader supplies to the four consonants. Today many Hebrew scholars prefer Yahweh as the true pronunciation."
-from Watch Tower, Jehovah's Witnesses official website "Identifying the Only True God"