Which is the correct words?

He spent one and a half hour / hours taking after his children.
Veteran Member7,394
The common way to say that is an hour and a half.

Since one and a half is greater than one you should use the plural hours (pure math).
Senior Member3,532
Moderator: A super-user who takes care of the forums. You have the ability to message a moderator privately should you wish. These users have a range of elevated privileges including the deletion, editing and movement of posts when needed.
a half hour
Veteran Member92,039
SystemAdministrator: A system administrator takes care of the inner workings of the entire system. These users have the ability to promote, ban and modify other users.Teachers: Users in this role are certified teachers. This may include DELTA, CELTA, TESOL, TEFL qualified professionals. Email a scan of your qualification to an admin, if you wish to be considered.
Note: not "taking after" but "looking after."
Veteran Member27,495
Proficient Speaker: Users in this role are known to maintain an excellent grasp of the English language. You can only be promoted to this role by the Englishforums team.Retired Moderator: A moderator who has retired.Trusted Users: Trusted users are allowed to use additional capabilities of the site such as private messaging to all users and various other advanced features. You cannot join this role unless you are promoted by an administrator.
I've done some investigating. It seems that both one and a half hour/hours are common. I guess it could go either way depending on how you parse the phrase.

one (hour) and a half hour.

(one and a half) hours.
Moderator: A super-user who takes care of the forums. You have the ability to message a moderator privately should you wish. These users have a range of elevated privileges including the deletion, editing and movement of posts when needed.
Thank you very much!!
Vincent TeoHe spent one and a half hour / hours taking after his children.
In the context of your question the only one that sounds right to me is "one and a half hours."
And "taking care of" not "taking after."

Note however that in other contexts "one and a half hour" is correct, as in these examples:

A one and a half-hour narrated sightseeing cruise.
A one and a half hour ride taking in the stillness of the early morning.
Contributing Member1,732
Proficient Speaker: Users in this role are known to maintain an excellent grasp of the English language. You can only be promoted to this role by the Englishforums team.
Live chat
Registered users can join here