The Vampire Diaries actor, 35, and Twilight's Nikki, 26, were spotted leaving the gym together and heading to the actress's house, fuelling rumours that they are dating.
Although neither of them have addresses the hearsay, both Ian and Nikki have been interacting with each other on Twitter.
Just last week, the actor retweeted a message from Nikki in which she urged fans to adopt a dog in need.
iamnikkireed's photo http://t.co/SVKyJFeaLf some one please give Kate a GREAT HOME!!!! PLEASE!— ian somerhalder (@iansomerhalder) July 23, 2014
It's not the first time the duo have been pictured together. Last week they enjoyed each other's company at a local farmer's market. At one point, the gorgeous brunette beauty and Ian hugged as they checked out the fresh produce on show.
Ian has been single since May 2013, when he split from Vampire Diaries co-star Nina Dobrev after three years of dating. However, the two remain amicable exes.
Speaking to Nylon magazine following the split, Nina said: "I don't like any kind of negativity. I try to be good to everyone, whether it's a love, a friend, an ex,. I'll always try to treat people the way I want to be treated."