Father Kenny was born near Zaleski, Ohio, on October 12, 1864, the youngest child of Irish immigrants from County Clare. After attending St. Joseph's College in Bardstown, Kentucky, and St. Xavier College (later Xavier University) in Cincinnati, he entered the Society of Jesus at Florissant, Missouri in 1883. Four years later he moved to Woodstock College in Maryland, where he studied philosophy.
Kenny began to teach at Marquette College (now University) in Milwaukee, St. Mary's College in Kansas, St. Ignatius College (now Loyola University) in Chicago, where he spent six years, and Creighton University in Omaha. He also lived for a year at St. Ignatius Mission, Montana, which served the Salish (Flathead) Indians, before returning to Woodstock for theological studies. In 1900 he was ordained a priest in St. Francis Xavier (College) Church in St. Louis, a member of the first class to receive major orders there.
Kenny taught at Saint Louis University from 1900 to 1931, rising to head the Department of History before transferring to the University of Detroit, which he referred to as the place of his "exile." In 1937 he returned to teach in St. Louis as a simple professor. Kenny specialized in American history, especially that pertaining to the Catholic Church in the United States.
Kenny published widely in both Catholic and secular journals, and for some years, ending in 1919, was American correspondent for Rome's CIVILTA CATTOLICA, "said," as he noted, "to be the magazine that the Pope always reads." He also served as Chaplain to the Missouri Council of the Knights of Columbus, and helped to found the Catholic Educational Association in 1904. He was counselor to eleven presidents of Saint Louis University.
Of his historical work, Kenny was particularly proud of his research on the Gallipolis Colony, the first Catholic colony to be established in the United States. He observed that Bishop Shahan of the CATHOLIC HISTORICAL REVIEW, which carried the piece, believed it "the most valuable piece of reconstruction of American history that this publication had carried up to that time." Kenny also established the site of the first white settlement in Missouri, a mission called St. Francis Xavier set up by Jesuit priests, Kaskaskia Indians, and white traders at the mouth of the River Des Peres in South St. Louis. Kenny was intent, too, on settling the claim of Saint Louis University to be the oldest Catholic university in the country.
Kenny called his classes "American history taught by an eyewitness." He met Geronimo and Theodore Roosevelt, and was considered the last living link with the founders of Saint Louis University through his seminary studies with one of these men. He expressed his philosophy of history as one of optimism, of the delight of recognizing "the perpetual vision of the rainbow of Christian hope." As for American history in particular, Kenny believed "that American rulers, both in church and state, when one considers the thousands of mistakes of most serious nature that they might have made and the few they actually made, are deserving on the whole of high commendation even reverence."
During his final years, Kenny was a patient at Mt. St. Rose Hospital in St. Louis. When he died on December 28, 1959, he was 94 years old and had been a religious for 76 years, making him the oldest Jesuit in the United States.
Kenny's attempts to broaden familiarity with the history of the Catholic Church in America and to emphasize the contributions of Catholics to the larger American culture were efforts to honor diversity by striving for inclusion, although his concentration on the Catholicity of historical figures and on Catholic "firsts" can strike the reader as annoyingly parochial. His uplifting view of the historical record may now seem naive, but was the hallmark of a patriotic American and devout Catholic of his time. As his comments against racial bias and segregation demonstrate, Kenny was sympathetic to the need for social reform, yet his cautious approach to schemes like the Townsend Plan of 1934 show him to have been essentially conservative in thought. No matter what his sociopolitical views may have been, however, Kenny's careful research and lively if dated writing style give his work enduring value.