Sarah Jessica Parker attends Did You Hear About The Morgans premiere
The film tells the story of a couple, already struggling with relationship problems, who witness a murder and are re-located to a small town for their protection.
Speaking about his co-star, Grant said: "She's not at all actressy or Hollywood or starry, she's just a good egg and funny."
Directed by Miss Congeniality writer Marc Lawrence, the film also stars Sam Elliott.
Grant also praised the director, telling ITN: "I love Marc, I did Music and Lyrics with him and Two Weeks Notice. I like his humour, his scripts make me laugh.''
Actress Elizabeth Hurley, along with her husband Arun Nayar, also attended the premiere.
Sarah Jessica Parker has recently been working on the new instalment of Sex and the City franchise, where she plays the role of relationship columnist Carrie Bradshaw.