Ashton Kutcher shared a flight with Demi Moore on Monday, September 9.
The Two And A Half Men star, 35, was photographed chatting with his estranged wife, 50, whom he split from in November 2011, as they left Burbank airport in Los Angeles together shortly after arriving there on the same plane.
A source told gossip website TMZ.com that the duo, who were married for six years but split when it was revealed that Ashton had a fling with a student two years ago, ran into each other at a technology conference in San Jose, California.
The former couple appeared to be in good terms despite previous reports Demi has been holding up their divorce as she is seeking spousal support and legal fees.
Ashton filed for divorce from Demi in December 2012 but their divorce has not yet been finalized.
The actor's girlfriend Mila Kunis, 30, sparked speculation they are engaged after she was spotted wearing a gold band on her engagement ring finger, while purchasing flowers in Studio City, California, last month.
A source recently said: "They plan to get engaged soon. Being with Mila brought Ashton back to who he really is.
''He's not playing the field, he's focused on enjoying Mila and the happiness she brings. She doesn't get jealous like Demi used to. He calls her because he wants to and when they're apart they talk constantly.''