Bruno Stanley Kowalkowski was the eldest of the five children of Bruno Kowalkowski and Rose Therese Chytla. Born in the Pilsen area of Chicago on August 16, 1929, he attended St. Pius V and Notre Dame grammar schools and Crane Technical High School. At the age of eighteen years he assumed a parental role in the home when his father left home. As his mother worked nights, he worked at a Chicago printing company turning over his paychecks to the family. Because of his athletic skill he was for a time at the Chicago White Sox training camp.

On August 30, 1957, he fulfilled a long-standing desire and entered the Dominican novitiate at St. Peter Martyr Priory, Winona, Minnesota, where he received the religious name of Hyacinth. A year later he professed his first vows there on August 31, 1958, and was assigned to St. Thomas Aquinas Priory, River Forest, Illinois, to pursue his philosophical studies, earning a Bachelor of Arts degree. He made his final profession on August 31, 1961, and was assigned to St. Rose of Lima Priory, Dubuque, Iowa, where he spent the next four years studying theology. Bishop George Biskup, auxiliary of Dubuque, ordained him a priest on April 18, 1964.

In September 1966, Father Kowalkowski began his first assignment as a priest at St. Margaret Parish, Boyce, Louisiana. A year later he was assigned to the foreign missions in the Vicariate of Nigeria, West Africa, which was to be the scene of his priestly ministry for the next fifteen years. For a short time he served as an associate pastor at St. Dominic Parish, Yaba, Lagos, but was then assigned to St. Vincent Ferrer Parish, Malumfashi, Northern Nigeria (1966-74). For the next three years he served as associate pastor of St. Dominic Parish, Yelwa, Northern Nigeria, and in 1978 was named administrator of Holy Family Cathedral, Sokoto, Nigeria, a position which he filled until his return to the United States in early 1981.

After completing a course at the Institute for Clergy Education, University of Notre Dame, Notre Dame, Indiana, and a Clinical Pastoral Education program at Alexian Brothers Medical Center, Elk Grove Village, Illinois, he began what was to be nine years of ministry as a hospital chaplain, first at Alexian Brothers Medical Center (1982), then at Hines VA Hospital, Maywood, Illinois (1983 -89), and finally at St Luke's Hospital and VA Hospital, Fargo, North Dakota (1989 -91 ). In 1991 he took up full-time preaching ministry while residing at Holy Rosary Priory, Minneapolis, Minnesota, and continued until 1994 when he was assigned to St. Pius V Priory, Chicago, Illinois. There he served the community as business manager until his death. During this time he also did occasional hospital ministry at Hines VA Hospital, Maywood, Illinois, and at St. Anthony Hospital, Chicago, Illinois.

Although diagnosed with prostate cancer, Father Kowalkowski continued to serve the St. Pius community. In the spring of 1998, it was confirmed that the cancer had spread to the bone. The cancer became increasingly aggressive and in June he moved to the Juan Macias Care Center, River Forest, Illinois. His condition continued to worsen throughout the summer and on August 10, 1998, surrounded by his family and his Dominican brothers, he died as the Friars sang the Salve Regina. The Mass of Christian Burial was celebrated at St. Thomas Aquinas Priory, River Forest, Illinois, on August 13, 1998, and he was buried in the Dominican plot at All Saints Cemetery, Des Plaines, Illinois.