Nicole Kidman has shouted 400 sick Sydney kids to a screening of her new movie, the animated hit about singing, dancing penguins, Happy Feet.

Australia's biggest international movie star, who is in town on a brief pre-Christmas visit, hosted the screening at Sydney's Fox Studios for the young patients of the Sydney Children's Hospital.

"It's just lovely to be able to come and do something for the kids," she said.

And speaking to the excited youngsters before the screening, she said: "I want to say thank you because you all inspire me."

Happy Feet, scheduled to open in Australian cinemas on Boxing Day, was directed by George Miller and features the voices of an all-star Australian cast, including Kidman, Hugo Weaving, Steve Irwin, Anthony LaPaglia, Magda Szubanski and Hugh Jackman.

It's the first time Kidman, 39, has been home since her lavish and romantic June wedding to country superstar Keith Urban.

But a relaxed and smiling Kidman showing no signs of the strain caused by Urban, also 39, who is in rehab in the US in his latest battle against alcoholism.

Kidman is believed to be making the lightning visit to her hometown to discuss her next movie project, Australia, with famed director Baz Luhrmann.

She will star in the World War II epic with fellow Australian superstar Hugh Jackman. Filming is expected to begin in March.