Meriam Yehya Ibrahim, 27, was convicted by a Khartoum court this week of apostasy, or the renunciation of faith.
The court considers her to be Muslim.
She also was convicted of adultery.
Ibrahim’s lawyer Haram Othman told CNN that her legal team will appeal the verdict within 15 days.
According to the rights group Amnesty International, she was convicted of adultery because her marriage to a Christian man was considered void under Sharia law. She was sentenced to 100 lashes for the second crime.
“The verdict is contrary to commitments Sudan has made in its own Constitution and commitments made under regional and international law; Meriam has been convicted solely on account of her religious convictions and personal status,” said Katherine Perks with the African Centre for Justice and Peace Studies.
“The fact that a woman could be sentenced to death for her religious choice, and to flogging for being married to a man of an allegedly different religion, is abhorrent and should never be even considered,” Manar Idriss, Amnesty International’s Sudan researcher, said in a statement.