I've seen the following sentences used. Tell me if both are right.

"He is 30 YEARS old. "
"He is a 30 YEAR old man."
Thanks for that note, learner - I always wondered why there is no -s Emotion: smile
Both are fine.

But you have to write the second one like this:

"He is a 30-year-old man." ("30-year-old" functions as an adjective, so you take the "s" out..)
Site Hint: Check out our list of pronunciation videos.
 Pemmican's reply was promoted to an answer.
Is it right to say
He is 30 YEAR old.
no.. It is not..

"He is 30 years old" or "He is a 30-year-old man"..
Students: Are you brave enough to let our tutors analyse your pronunciation?