Armie Hammer: Kissing Leonardo DiCaprio for J. Edgar wasn't weird
The biography, which is set for release in the US later this year, also stars Josh Lucas, Naomi Watts, Ed Westwick, Lea Thompson and Judi Dench.
It focuses on the story of FBI director J Edgar Hoover, telling of his career and controversial private life.
In the film, Hammer plays Hoover's (DiCaprio) rumoured gay lover Clyde Toulson.
But Hammer said he didn't mind the experience.
"It wasn't that weird. I have never kissed a guy - it's not something I'm going to do in my private life, but at the end of it I was, like, 'Man, there is a lot of weird hype'," he explained.
Hammer, who previously starred in The Social Network, 2081 and Gossip Girl, is expected to star in The Brothers Grimm: Snow White, alongside Lily Collins and Julia Roberts.