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Dr. Joseph F. Demendi | 89

May 2, 1932 - January 23, 2022

Dr. Joseph F. Demendi of Crystal Lake, Illinois, passed away on Sunday, January 23, 2022 at his home at the age of 89 after a short illness. Joseph grew up in Gyula, Hungary, where he met his childhood sweetheart at age five and declared that he would marry her. Mary Jeszenszky and Joseph married on St. Joseph’s feast day, March 19, 1955. Joseph was a very tenacious and persevering man who found ways to overcome many challenges in his life. Joseph, his wife and infant daughter left Hungary in December, just after the failed revolution of October 1956. The National American Academy of Science sponsored him to come to the U.S.

Joseph made his home and raised his family in St. Marys, PA and after 27 years moved to Strongsville, OH for a brief period, and then to Crystal Lake in 1992, where he remained until his death.

With a degree in Chemical Engineering from the Technical University of Hungary and a Ph.D. Summa Cum Laude in Physical Science from the University of Strasbourg, France, Joseph had a long career and worked for several companies such as the former Pure Carbon of St. Marys and John Crane of Morton Grove, IL. With wide recognition in the U.S. and abroad he used his expertise in carbon processes and friction technologies designing and building friction and seal components for rockets, airplanes and space shuttles, to mention a few. He obtained many patents for his work. In the last decade he designed and built coking ovens for companies like Saint-Gobain.

Joseph was preceded in death by his wives, Mary Demendi and Elizabeth Demendi.

He loved his family, friends and cherished the memories he made with them. Joseph is survived by his children, daughter, Lillian Connor (Mark) of Charlottesville, VA, and his son, Joseph Demendi Jr. of Crystal Lake, IL; grandchildren, Justin Connor and Agnes Clement (Claude) of Charlottesville, VA, Alycia Demendi (Ryan) of Crystal Lake, IL, Brittany Demendi of Tampa, FL and Celeste Demendi of Long Branch, NJ; great-grandchildren, Bode, Harper and Madeleine.

An avid chess player, Joseph was known to snag any willing victim to play every chance he could get. He repaired cuckoo clocks and even refurbished an anniversary clock. He enjoyed candle making for a while, ordering different gauges of wicks and pouring anew wax from remnant candles. Cooking was easy for him as it was just “chemistry” with food. Joseph relished cooking and baking with his granddaughters, teaching them all the standard Hungarian and German dishes. He was smart and liked passing on what he knew by telling stories, teaching Latin proverbs and lessons from history. He will be missed.

There will be no visitation.

Family and friends are invited to attend a Mass of Christian Burial to be celebrated in the St. Mary’s Catholic Church on Wednesday, February 2, 2022, at 11:00 AM, with the Rev. Peter Augustine Pierjok, OSB, Pastor, officiating. Burial will follow in the St. Mary’s Catholic Cemetery.

Memorials, if desired, may be made to the American Heart Association, 15120 Collections Center Drive, Lock Box 15120, Chicago, IL 60693 or to the National Fragile X Foundation, 1861 International Drive, Suite 200, McLean, VA 22102.



No Visitation

Funeral Service

February 2, 2022
11:00 am
St. Mary's Catholic Church

Final Resting Place

February 2, 2022
12:00 pm
St. Mary’s Catholic Cemetery

Tribute Wall


  1. Lillian and Joe – Larry sent your dad’s obituary to me – so very sorry to hear about your father’s passing. I have many fond memories of your mom and dad and living next to all of you in St Marys. Thinking of you during this time and offering our sympathy to you.

  2. I did not know Dr. Demendi, but I grew up hearing about him. My father, Fank Hoffman used to work with him at Pure Carbon. My dad had the most utmost respect for him and talked about what your father went through coming to our country. Years later, George Daghir would tell me stories of your father and my father. I wish that I had had the chance to have met him. I am very sorry about your father’s passing. My sympathy, prayers and thoughts are with you.

  3. So sorry to see that our dear friend has passed. We lived next door to Joe for many years in Crystal Lake- he was the best neighbor we’ve ever had and had such a big loving heart! Our condolences to the family…

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