Ernst Marno first worked in the field of zoology and made in 1866 in support of the animal trader Casanova a trip to the border with Abyssinia. He went in 1869 to Khartoum, where he penetrated through the Sennar south to Fadasi.
1870 traveled Marno individual parts of Fasokl, 1871 and 1872, the areas along the Bahr el- Seraf and upper Bahr el- Abiad, reaching Gondokoro, where he met Samuel Baker. From there he returned to Vienna.
Later he was appointed Gordon Pasha at the upper Nile, but only reached Lado. Because of disagreements he then joined Charles Chaillé - Long and went into the Makarakaland. Then he made detailed studies in Kordofan and returned in 1876 back to Europe.
The International African Association in 1877 sent an expedition to the East African coast from which even Marno joined. The expedition undertook in January 1878 a trip to the countryside Usagara, but soon had to return due to health reasons from the Marno. He went back to Gordon in 1879 and became a top official of the province Galabat.
Ernst Marno died on 31 August 1883 in Khartoum.
In 1894 in Vienna Penzing ( 14th district ) was named the Marnogasse after him.
Marno was a member of the fraternity Olympics since 1863.