In February 2008, Kim was announced as the female lead in Park Chan-wook's Thirst, in a part that required numerous adult scenes with co-star Song Kang-ho. Kim felt that she learned much from working alongside Song, while Park commended her versatility in showing the different sides to her character. Thirst topped the South Korean box office during its opening weekend with over one million admissions, and was invited to the 2009 Cannes Film Festival where it won the Jury Prize. Richard Corliss of Time praised Kim's performance in the film, saying, "It's the lovely Kim, just 22, who is the revelation here. She can play — no, she can be — a creature of mute docility, then searching ardor, then explosive eroticism, then murderous intent. She is Lady Chatterley and Lady Macbeth in one smoldering package." The Hollywood Reporter's Maggie Lee was more critical, commenting, "[Kim's] high-pitched neurosis is sometimes grating, but for a relative newcomer, she keeps her continuous personality transformations in stride," while Kyu Hyun Kim of OhmyNews said, "Kim is stunningly sexy in both wilted-housewife and full-blown femme fatale modes, and throws all of herself into the role," but considered her "a bit too young and contemporary" for the role. She was a co-recipient of the Best Actress award at the 42nd Sitges Film Festival (shared with Elena Anaya for Hierro), and received further nominations at the Blue Dragon Film Awards, the Green Globe Film Awards, and the Baeksang Arts Awards.