When was imperio curse in Harry Potter and orden of phoenix?

The Imperius Curse is used in Harry Potter and the Order of the Phoenix, but not in the specific sense of being used on Harry himself. It's used by the Death Eaters who break into the Ministry of Magic, and they use it on several Aurors to control them and gain access to the Department of Mysteries.

The scene occurs in Chapter 36, "The Department of Mysteries", after the Death Eaters attack and break through the Department of Mysteries.