Edmund D. Pellegrino, a physician and a student of medical ethics, will be inaugurated Friday as the 12th president of Catholic University at the Shrine of the Immaculate Conception on the university campus.

Pellegrino took office last September as the second lay president of Catholic University, succeeding Clarence Walton who resigned to resume a career in teaching and research. Pellegrino will be formally ingugurated at a 3 p.m. convocation at which Vice President Walter F. Mondale will deliver the keynote address.

A graduate of St. John's University in Brooklyn and New York University Medical School, Pellegrino came to catholic University from Yale University where he was founding president of the Yale-New Haven Medical Center and a proffessor of medicine of Yale.

At Catholic University, he heads a faculty of 600 and a student body of 8,000 spread over a 180-acre site in Northeast Washington.

The only university in the United States established under direct papl sponsorship, Catholic University is governed by a constitution approved by Pope Leo XIII in 1887. Two year later it opened to a student body of 30 priests taught by a faculty of 12 other priests. Today it is made up of nine schools which grant master's, bachelor's and doctoral degrees in 40 fields.

Friday's inaugural ceremony caps a week of activities that began last Sunday with a convocation in the Hartke Theater at which Pellegrino presented the University's Presidential Medal for Distinguished Service to Winifred L. Bouftreaux and Mary E. Murray, respectively the immediate past national regent and the national regent of the Catholic Daughters of America.

On Wednesday, composer Aaron Copland was scheduled to receive an honorary doctor of music degree, and California businesswoman and cultural leader Caroline Ahmanson was set to receive an honorary doctor of humane letters degree at ceremonies in the hartke Theater.

Inaugural day Friday will begin with a 10 a.m. Mass of the Holy Spirit at the Shrine of the Immaculate Conception. Cardinal William Baum, the Catholic archbishop of Washington and chancellor of the university, will be both celebrant and homilist.

A native of newark, N.J., Pellegrino grew up in Brooklyn and served on medical and research faculties at the University of Kentucky, the State University of New york st Stony Brook, and the University of Tennessee before taking the post at Yale in 1974.

Married and the father of seven children, he likes music, book collecting, tennis, reading and writing poetry in Latin in his spare time.