John P (Jack) Hennessey, 88, passed away peacefully on Friday, June 26, 2026. He was surrounded by his family who love him deeply and will cherish and honor his memory forever.

Jack was born in Cohoes, NY in Dec 1937, the son of the late Julia J. and John P. Hennessey. He was also predeceased by his only sister Patricia Horton in 2014.

Jack is survived by his beloved wife of 65 years, Rosemary (Rourke) Hennessey, his three children Jay (Laura) Hennessey, Janice (Joseph) Costello and Lynn (Michael) Pandori; grandchildren, JP (Zack) Hennessey, Shannon (Steve) Tramposch, Connor Hennessey, Julia (Ryan) Kasarda, Jenna Costello, Adam and Tyler Monroe and Matthew Rourke; and great grandchildren Wren and Piper Tramposch. Additionally, his life has been deeply touched by nephew Joseph (Joanne) Rourke.

Keveny Memorial Academy in Cohoes, NY was the site of his early education where he graduated as Valedictorian in 1955. During his time there, the nuns recognized his academic potential and encouraged him to pursue higher education. Jack continued to be active in his Alumni reunion activities for many years. Jack went on to earn a BS in Electrical Engineering from Rensselaer Polytechnic Institute in Troy, NY in 1959, and in 1974, he earned a Master of Engineering Administration from Syracuse University.

Jack retired from Niagara Mohawk in December 1993 where he was Senior Vice President for Electric Customer Service. He began his career with the company in 1959 when he joined the engineering department in Albany. In 1967 he was transferred to Syracuse and progressed through various positions until he was elected Vice President of the company's data processing organization in 1978. In 1982, he was elected a Senior VP and had a variety of key assignments covering many departments within the company including engineering, hydro and fossil generation and both electric and gas field operations. When the company was reorganized into business units in 1990, he was appointed to head up the largest one, Electric Customer Service.

He served as a member of the board of ARC of Onondaga and was on the board of the Erie Canal Museum for ten years until 1994. From 1987 to 1993 he was a Director of the Utility Mutual Insurance Company.

In May 1960, he met the love of his life, Rosemary Rourke. Rosemary often said that the minute she met him, she knew he was the one she would spend her life with. They married on July 1, 1961, and remained steadfast in their love and commitment to each other and their family throughout their 65 years of marriage. Their life together was anchored by an undeniable love, a deep and unwavering faith, and a commitment to live each day with kindness, gratitude, humility, and service. Their relationship will forever serve as an inspiration to our family.

Jack's focus throughout his life was his family. He took great pride in the achievements of his children and grandchildren, consistently serving as a role model, teacher, financial planner, problem solver, and confidant. His wisdom and guidance were unparalleled.

Since 1968, he was an active communicant of St. Mary's Catholic Church in Baldwinsville. In the mid-seventies, he served as president of the parish council, and over the years, contributed as a Mass Lector, Eucharistic Minister, and most recently, as a funeral Altar Server. He and Rosemary attended Mass weekly, raising their children with a strong foundation in the Catholic faith.

Following his retirement, he volunteered for Habitat for Humanity until mid-2010. Subsequently, he was a founding member of Silverhammers, a non-profit construction group, which raised over $300,000 for local charities. He loved this charitable hands-on work and the many friends he made there.

His recreational activities included tennis at Sedgwick Farms, Drumlin Tennis Club in Syracuse and Bay Oaks Club, Ft. Myers Beach Florida, where he and Rosemary spent several months each winter. Over the years, he made many close friendships with what he affectionately called his 'tennis buddies.' In more recent years, he discovered pickleball and played at various courts, often proudly being the most senior man on the court.

The family would like to recognize and thank the doctors and staff at St. Joseph Hospital for their skill and compassion in treating Jack. His ability to connect deeply with others during his hospitalization stands as a testament to his character and kind heart.

Friends and family are invited to pay their respects and honor Jack's life from 4:00-7:00pm Thursday, July 9, 2026, at Falardeau Funeral Home, 93 Downer Street, Baldwinsville, NY. A Mass of Christian burial will be celebrated on Friday, July 10, 2026, at 11:00 am at St. Mary's Church, 47 Syracuse Street, Baldwinsville NY with burial immediately following at St. Mary's Cemetery, Tappan Street, Baldwinsville.

Contributions may be made to Brady Faith Center or the Samaritan Center in Syracuse NY.