The Australian actress admits shooting the project with Clive Owen as Gellhorn's husband Ernest Hemingway reignited her own interest in creative writing.
She tells Britain's Daily Telegraph newspaper, ""I write for myself - it's my way of letting myself go. It's purging. I first stumbled into it as a teenager.""
Kidman was so passionate about the news as a child, she told her clinical psychologist father she dreamed of becoming a reporter.
She recalls, ""When I was 10, I would say to my father, 'I want to be a journalist.' The thing he least wanted me to be was an actress. I still haven't received that approving nod!""