Born in Surbiton, Kingston upon Thames on 4 October, 1854 (GRO) into a large and wealthy German merchant family, Detmold  studied at Atelier Carolus Duran in Paris, and in Dusseldorf, Munich and Brussels.

He arrived in Newlyn around 1885, and is mentioned as one of the Newlynites who comprised the original Newlyn colony.  He played as part of the Newlyn team in the cricket matches that transpired against St Ives, and also in the Artists of West Cornwall XI against Penzance (1888).  In 1889 he took lodgings for a few months in St Ives, at 7 Bellair Terrace, as many of the early Newlyners did.  

The subjects he painted were scenes in England, France, Cairo and North Africa.  He exhibited his work in the newly refurbished Lanham's Gallery in 1898, and took part in the Dowdeswells Exhibition of 1890 with three paintings.  By that time, however, he was living in London, having married Miss Julia Lane (b 1863 in Mensthe & Moselle, France). They subsequently lived in Hastings and St Leonards from around 1892, before giving an address in Paris in 1900.

He is mentioned in one of Stanhope FORBES' letters in 1885, and was known to stay at Belle Vue House, Newlyn, remaining only six months before moving to Cliff House in Fore Street.  Much more aligned with Newlyn than St Ives, he was nevertheless a founder member of STIAC during his brief time there, shortly thereafter leaving for London.

Henry Detmold was the uncle of the highly regarded artist twins, Charles Maurice DETMOLD (1883-1908) and Edward Julius DETMOLD (1883-1957), and helped another sister and brother-in-law to bring up their nephews as visual artists and illustrators. 

The artist died in Paris, and is buried in the Pere Lachaise cemetery.