SOUTH BEND, Ind. -- Joan B. Kroc, the billionaire widow of McDonald's Corp. founder Ray Kroc, left $50 million to the University of Notre Dame in her will for the peace studies institute she helped create.

The bequest is the largest single gift in Notre Dame's history, the university said today. Kroc died Oct. 12 of brain cancer at the age of 75.

"Words cannot adequately express our deep gratitude for this monumental gift," said the Rev. Edward Malloy, the university president.

The money will be used to establish the Rev. Theodore M. Hesburgh Fund for Graduate Peace Studies at Notre Dame's Kroc Institute for International Peace Studies.

Money from the endowment by the Kroc Institute graduate program adds staff and faculty with expertise in peace studies and develop of classroom education and clinical training.

Kroc met Hesburgh, who was then Notre Dame's president, in the mid-1980s at an event in San Diego during which he voiced his concerns about the escalating arms race.

In response, Kroc made a $6 million gift to Notre Dame in 1986 to establish the peace studies institute.

She made an additional $6 million gift two years later to build Notre Dame's Hesburgh Center for International Studies, which houses the Kroc Institute and the Helen Kellogg Institute for International Studies.

She donated another $5 million in May for Hesburgh's 86th birthday to create in his name a fund to provide scholarships for students in the institute's graduate program.

In all, she has contributed $69.1 million to Notre Dame.

The previous largest donation to Notre Dame was a $35 million naming gift from Thomas and Kathy Mendoza for the Mendoza College of Business.