Jennifer Lawrence chants for equal pay

Jennifer Lawrence chanted for equal pay while at a pre-Oscar party celebrating the achievements of women in Hollywood.

The Joy star, who is up for Best Actress at the Oscars, made a surprise appearance at the Ninth Annual Women in Film Pre-Oscar Party in West Hollywood, Los Angeles, on Friday.

The 25-year-old actress, who has already sparked a debate on equal pay in the movie industry, took to the stage with Women In Film LA president Cathy Schulman and made an impromptu speech, Entertainment Tonight reports.

Jennifer admitted to a serious case of nerves as she spoke right after fellow actress and women's rights advocate Patricia Arquette, who talked to the audience about her change.org/era petition, which was created to urge lawmakers to vote to ratify the Equal Rights Amendment.

"I'm a huge fan of Patricia Arquette," Jennifer told the crowd. "I actually played the younger version of her (on the crime show Medium). I love that she stood up, for starting a conversation. We're getting dialogue going. I'm going to go home, and I'm going to go to change.org/era... I'm going to that. Let's all do it."

The actress then finished her speech with a rousing chant, "Equal pay, woo!"

Back in October, The Hunger Games star wrote an essay for Lena Dunham's newsletter Lenny Letter, in which she addressed her experience with pay inequality in the film industry after she discovered she was paid less than her male American Hustle co-stars.

The event, which honours all 51 women who have been nominated for an Oscar this year, was also attended by Alicia Silverstone, Michelle Monaghan and Sasha Alexander.

The Oscars is on today and Spy.co.nz is bringing you all the action. Spy Editor Ricardo Simich joins The Hits host Polly Gillespie and NZME's Laura McGoldrick to deliver our take on who got it right and who got it wrong on the red carpet. Tune in for our live blog from 11.30am and don't miss our Red Carpet Report video, live on Spy.co.nz from 5pm.