Iwao Kohatsu

Dr. Iwao Kohatsu, a retired ceramics and metallurgy scientist, passed away on Saturday, August 8, 2026, at the age of 86 in Chicago, Illinois.

Born in Kobe, Japan, on August 2, 1940, Dr. Kohatsu began his academic journey at the Tokyo Institute of Technology. After receiving a U..S. Military scholarship while living in Okinawa, Iwao continued his academic studies in ceramics and materials science at Penn State University where he earned his Master's Degree. He went on to earn his Ph.D. in Materials Science from the Massachusetts Institute of Technology where his doctoral dissertation focused on the crystal structure of complex sulfosalts. During his education, he had the opportunity to study under renowned materials scientist Rustum Roy (Penn State) as well as Professor B. J. Wuensch (MIT).

From 1971 to 1973, Dr. Kohatsu served as a postdoctoral fellow at the Army Materials and Mechanics Research Center in Watertown, Massachusetts, where he conducted research in ceramic science. He later joined Chevron Research in Richmond, California, where he pioneered work using X-ray absorption fine structure (XAFS) to study the fine crystalline structure of semi-amorphous materials. For the remainder of his scientific career, he contributed to the development of advanced ceramic materials while employed in research laboratories at Dow Chemical Company and Cabot Corporation. Prior to his retirement in 2003, he led the consulting company Sumitomo Metal Mining (USA), helping foster collaboration between Japanese and American scientists in the development of new ceramic technologies.

While Dr. Kohatsu (Iwao) was an accomplished scientist by profession, he will be remembered most for the life he built outside the laboratory as a husband, father, grandfather, brother, and friend. He approached life with determination, independence, and a deep sense of principle. Iwao’s “let’s try it!” attitude created many adventures that will live on as cherished memories. Yet beneath that serious exterior was a warm sense of humor, a broad smile, and an ability to chuckle at himself that endeared him to family and friends.

During his earlier marriage to Judith Jenkins Kohatsu of Ocean City, New Jersey, Iwao welcomed twin daughters. A devoted father, he raised his daughters in Lexington, Massachusetts, where the family lived for more than twenty years. As a father, he quietly filled whatever role was needed, always finding ways to support his family, whether staying up late to help with homework, making maki sushi at the last minute for his daughter’s school project, or building a balance beam in the living room. He also loved getting his family out into nature to hike, camp, learn to alpine ski together (beginning himself at nearly 50 years old), and enjoy his favorite pastime, canoeing. In his free time, Iwao took his kids, and later grandkids, to Red Sox games, played tennis with friends, and tackled quirky do-it-yourself home projects by engineering creative solutions.

Retirement to Windham, New Hampshire, brought Iwao the opportunity to travel extensively with his wife, Keiko, throughout the Baltic region, the Mediterranean, and Asia. When he became a grandfather, he was amazing at it. His four grandchildren knew him as someone who played, taught, encouraged, debated ideas, shared stories, teased, and, on occasion, practiced a little judo. He was an active participant in their lives, taking joy in learning and laughing alongside them.

At the age of 83, Iwao embarked on a new adventure by moving to Chicago. He lived independently in a condominium with views of Lake Michigan and the city skyline (a view he loved). In his new home, he enjoyed getting in his daily 10,000 steps along the lakefront, discovering neighborhood restaurants, and trying all that the city had to offer all the while wearing his Boston Red Sox cap. He attended the Lyric Opera, Chicago Symphony Orchestra, Chicago Fire matches, and DePaul basketball games and concerts. He picked up his grandson from school and attended his grandchildren's concerts, sporting events and school activities. He became a familiar face in the Lincoln Park community and a treasured part of his daughter's family, all while remaining fiercely independent.

Though he will be deeply missed, Iwao Kohatsu lived a full life, and his spirit and the values he lived by will live on in his family who loved him dearly. Ganbatte!

Iwao is survived by his daughters, Kay Kohatsu and her partner, Martin Witkowski, of Chicago, Illinois; Kathy Kohatsu and her husband, Matthew Toms, of Bethlehem, New Hampshire; his wife, Keiko Bunker of Nashua, New Hampshire; his sister, Mari Yamafuji of Yokohama, Japan; his brother, Takashi Kohatsu of Okinawa, Japan; and his beloved grandchildren, Kobe Toms and Asa Toms of Bethlehem, New Hampshire, and Sevah Witkowski and Sebastian Witkowski of Chicago, Illinois.