The Rev. Horace B. McKenna, 83, a Jesuit priest for 53 years whose ministry to the poor made him a revered figure among Washington's hungry and homeless, died yesterday at Georgetown University Hospital after a heart attack.

As an assistant pastor at St. Aloysius Church, at North Capitol and I streets NW, Fr. McKenna was the cofounder in 1977 of SOME (So Others Might Eat). It was a program operated from a fumigated former dog shelter at 71 O St. NW and it grew out of a daily sandwich line established at St. Aloysius rectory in the late 1960s. Five years ago, 200 citizens were served two meals a day at SOME. Yesterday, a volunteer reported the number of guests now totals 600 a day, and growing.

Archbishop James Hickey of the Archdioses of Washington said yesterday that Fr. McKenna was "a strong advocate and a devoted servant of the poor . From his days as a pastor in Southern Maryland to his long years in service in the District, Fr. McKenna has been a striking example of Jesus' call to serve 'the least of these.' "

A short, physically fit man who lived in a sparely decorated room next to the second-floor library in St. Aloysius rectory, Fr. McKenna's Irish friendliness often camouflaged his intensely burning drives for social justice and peace. Last month, he told an interviewer that the time had come for "some hunger marches . . . . We need something to make this man President Reagan realize that he's spending our food money on armaments."

Fr. McKenna's own willingness to march was on display as recently as August 1980 when he joined a large group of peace activists protesting an arms exhibit by the Air Force Association at a Washington hotel. Fr. McKenna said that "this intended war show" was turning the hotel "into a bargain basement for death, destruction and annihilation."

Among his fellow Jesuits of Washington, Fr. McKenna was a role model of a priest who combined service to the poor with a robust spiritual life. He embraced the modernized liturgies created after the Second Vatican Council, but the new trappings, he believed, were not meant to replace the enduring necessities of interior prayer and community worship.

As a young priest, Fr. McKenna went in 1931 to serve in St. Peter Claver parish in St. Mary's County, Md. He was to remain there, in service to the black poor, until 1953, when he came to Washington.

In his unpublished memoirs, a rich collection of stories about both his personal development as a priest and of friends as diverse as Dorothy Day and Cardinal Patrick O'Boyle, Fr. McKenna recalled a meeting in 1937 when southern Maryland landowners were told that the government would pay them for not growing wheat.

"I sat in the back with the black people, as I always liked to do . . . They were not landowners, they were laborers. They had to work the plows, and they had to work the thresher . . . So I stood up and I said to the speaker: 'You have made provision for the owner who doesn't plant. Now what provision are you making for the laborer?' Well, they turned around and looked at me as if I were Lenin or Trotsky! I thought it did them good to have some realization that the laborer was involved in these operations."

At St. Aloysius, Fr. McKenna relished the pastoral ministry: celebrating mass, hearing confessions, preaching the love of God, visiting the sick and the imprisoned, and raising money for the poor families of his parish. He helped establish Sursum Corda, a housing project for the poor. He also expanded SOME so that it offered medical care and counseling services.

Fr. McKenna, a cheerful man who delighted in sharing his wry comments with friends and strangers, spoke recently of his death: "When God lets me into heaven, I think I'll go off in a corner sometime for a half an hour, and sit down and cry, because the strain is off, the work is done, and I haven't been unfaithful or disloyal."

Fr. McKenna was born in New York City, one of 12 children of a chemist. He entered the Society of Jesus in 1916 at St. Andrew-on-the-Hudson in Poughkeepsie, N.Y., and was ordained in 1929. He received honorary degrees from four Jesuit colleges.