Romyn Hitchcock was born on December 1, 1851, in St. Louis, Missouri.

He was a research botanist, chemist, and educator. He attended Cornell University and graduated from Columbia School of Mines in 1872. He was an assistant professor of chemistry at Lehigh University, Bethlehem, Penn., (1872-1874) and engaged in testing heavy guns at the government arsenal in Springfield, Mass. (1874-1877). He taught chemistry and toxicology at the Chicago Homeopathic Medical College (1876-1877) and served as an editor of the American Quarterly Microscopical Journal and the American Microscopical Journal (1878-1886). From 1883 to 1886, he was a curator of the National Museum in Washington, D.C. He was professor of English at the Koto Chu Gakko, a Japanese Government school in Osaka (1886-1889), and oversaw the photographic work of the U.S. eclipse expedition to Japan in 1887. He also served as U.S. commissioner to China for the World Columbian Exposition (1887-1889). He later conducted botanical research. He was a Fellow of the American Association for the Advancement of Science and the Royal Microscopical Society of England and a member of the American Chemical Society, the New York Academy of Sciences, and the New York Microscopical Society.

In 1875, he married Emma Louise Bingham (1852–1933). He died on November 30, 1923, in Baltimore, Maryland.