J. Rowe Mehlfelt, 86, a retired industrial engineer at the old Naval Gun Factory who was active in the Knights Templar and other Masonic organizations, died of cancer Wednesday at Cleveland Memorial Hospital in Shelby, N.C.

Mr. Mehlfelt, who lived in Bethesda, was visiting a daughter, June Houlditch, at Kings Mountain, N.C., at the time of his death.

He was born in Waynesboro, Pa., and grew up in Washington. He graduated from McKinley Technical High School and George Washington University. He began his career at the gun factory in 1916. He remained there until his retirement in 1961.

Mr. Mehlfelt was a former grand commander of the Knights Templar of the District of Columbia and a past preceptor of the INRI Tabernacle. He also was a member of the Naval Lodge of the Brightwood Commandery, Potomac Commandery No. 3, Montgomery Knights Templar Lodge No. 13 and the Joppa Lodge Chapter of the Order of the Eastern Star.

He was a member of St. Paul's United Methodist Church in Kensington.

His wife, Irma V. Mehlfelt, died in 1978.

In addition to Mrs. Houlditch, survivors include a brother, Harry Mehlfelt of Silver Spring, a sister, Esther Liming of Edgewater, Md., three grandchildren, and three great-grandchildren.