He started drawing in 1942 during his Swedish military service. He was an expert in spacecraft, especially Soviet ones and worked as a translator from Russian during Juriy Gagarin visit to Sweden.
He also often worked as an illustrator for Aftonbladet, especially when the subject was related to space technology, he covered the Apollo space program as a journalist in Florida. As a Russian speaker, he got rare interviews with people involved in the Soviet space program. His non-fiction books covered actress Greta Garbo, science, speculative science such as possible future space colonies, starships using illustrations by known Space artists such as Fred Gambino and David A. Hardy. One interesting detail is that Eugen -at a time when the belief that aliens visited Earth was common - published one book on the subject which he deliberately gave a title and cover art to attract the 'true believers'. Where the bulk of the book was debunking a number of the most known UFO cases. He was the author of the science fiction comic Allan Kämpe, which was first published in December 1942. The stories might at first seem to be a simple copy of Flash Gordon, the comic has more in common with Sidney Jordan's, 'Jeff Hawke'. He also wrote a small number of youth novels. For his journalistic work Eugen Semitjov won Stora Journalistpriset 'The grand price for Journalism' in Sweden in 1972.