reading aloud - What is the correct way to write 1.5 hours?

I'm a bit confused in describing 1.5hrs in words.

Is writing one and a half an hour correct or should it be one and half hour?

E.g:

I'll see you there in one and a half an hour.

OR

I'll see you there in one and half hour.

Or is there any other correct way of writing this?

Answer

In general, for some number of hours, plus some fraction of an hour, you'd use the number, plus the fraction, plus "hours", plural. "Four and a half hours.", "Three and three-quarters hours," etc.

However, for the specific case of 1.5 hours, the usual expression is "an hour and a half". This usage is so common that "One and a half hours" actually sounds strange.