He was the son of Sir Hiram Maxim, inventor of the Maxim Machine gun. He was the nephew of Hudson Maxim, an inventor of explosives and ballistic propellants. He had two sisters, Florence Maxim, who married George Albert Cutter, and Adelaide Maxim, who married Eldon Joubert, Ignace Paderewski's piano tuner. In 1875, the family moved to Fanwood, New Jersey, with his father joining the rest of the family on weekends. At age 17, Hiram was a mechanical engineering graduate, class of 1886, of the Massachusetts Institute of Technology (then a two-year course). He went to work for various electric utility companies in Boston.