He was best known for China: a History of the Laws, Manners and Customs of the People (2 volumes, Macmillan, 1878) and his various other books on Chinese society, norms and history, including Walks in The City of Canton, which meticulously depicted the life of Canton in the 1870s.[2]
On 3 October 1876 in Hove, Sussex, he married Julia Cox (1838–1921) (who called him Henry), daughter of William Henry Cox, master printer, of London. They had two sons and two daughters (one of whom died in infancy). The surviving daughter married George Kruger Gray (1880–1943), notable heraldic artist.[5] John Henry Gray died at St Leonards on Sea, Sussex.