The couple already raise an 18-month-old daughter, India, together, reported Aceshowbiz.
According to reports, Pataky is three months pregnant and is due to give birth next spring.
"She's the best. It makes it harder and harder to leave and go to work. I enjoy being at home a lot more than I ever have. I think parenthood brings out the child in all of us. That's what's so beautiful. It reminds you of the fascination you had with things and how you can spend hours just being with someone. It's amazing," Hemsworth had said.