Gillard's book will be out in October

Former prime minister Julia Gillard has worked through a special kind of therapy after losing her job: writing a book.

My Story will be published on October 1 by Random House Australia.

Ms Gillard said writing the memoir had been exhilarating and cathartic.

"Sometimes the words flowed quickly and easily," she said on Wednesday.

"On other occasions, days of reflection were needed to work through memories of difficult times and the resilience required during them."

She promises the book will tell the truth about what it's like to be prime minister, what happened to her and why it matters for Australia.