Charlize Theron and Sean Penn appeared the perfect picture of a happy couple as they were snapped strolling hand-in-hand.

Rumours began circulating the 38-year-old Prometheus star and the 53-year-old actor were dating last year after they were spotted in Hawaii together, and they have since been seen on several occasions.

Now new pictures have shown Charlize and Sean looking loved-up as they walked hand-in-hand through the streets in the San Francisco Bay area. They headed to a garden centre where Sean bought the South African beauty a purple orchid.

Earlier this month the Oscar winners were photographed picking up food and other household items in a Whole Foods store in West Hollywood, accompanied by Charlize's adopted two-year-old son Jackson.

And the pair attended the Help Haiti Home gala in Beverly Hills together on January 11, where Sean reportedly told CNN's Piers Morgan at the event: "She's a keeper, that's for sure... well, I'll do my best to keep her anyway."