Born in Odžaci, former Yugoslavia, on October 9, 1920.
Studied at the University of Belgrade, the University of Berlin and the School of Fine Arts in Zagreb until 1945.
As a refugee in Austria at the end of the war, he becomes part of the Sezession group and teaches drawing at the School of Crafts in Graz.
In 1948 he emigrates to Brazil and starts working in Rio de Janeiro, in a poster company.
He makes friends with artists, including Portinari, Djanira, Henrique Boese, Santa Rosa and Thiago de Mello.
Held his first solo exhibition at the Ministry of Education in Rio in 1951 and began to participate in salons, biennials, etc.
Opened an advertising design studio with Ulisses Alvares Arce and in 1957 he founds Denison Propaganda S/A. In 1959, he moved to São Paulo.
He held 25 individual exhibitions in galleries and museums in Brazil and around the world, including the retrospective "25 years of Painting", at the Museums of Modern Art in São Paulo and Rio in 1970 and 1971, and the series "Brasil: Terra & Gente", at the São Paulo Art Museum and at the Petite Galerie in Rio, in 1976. In October 1977, he exhibited "Novas Notícias do Brasil" at the Global Gallery, after a trip to Alto Solimões. He has participated in more than 30 group shows, biennials and salons.
From 1974 onwards he began expeditions through the Amazon region.In 1978 Sepp promotes expeditions along the Purus, Solimões and Negro rivers, in the company of Frans Kracjberg and Pierre Restany, at the end of which Pierre Restany's text "The Rio Negro Manifesto - Integral Naturalism" is born.
In 1979, the three presented the Rio Negro Manifesto at the Beaubourg Museum (Centre George Pompidou) in Paris at a conference and presentation of the documentary film "Voyage to Integral Naturalism". These presentations were also made in Milan, Casablanca, Vienna, Tokyo, Rio de Janeiro, São Paulo, Brasília, Curitiba and at Columbia University in New York.
In 1980 Sepp and Frans Kracjberg carried out an Amazon expedition along the Amazon, Tapajós, Solimões and Jutaí rivers and in 1981 they exhibited images of the Amazon at Galeria São Paulo.
From 1981 onwards he travels through the Pantanal and shows drawings of the Pantanal fauna and flora at Galeria S. Sassoun, in São Paulo.
In the years 1984 and 1985, in the company of the poet João Carlos Meirelles and Franz Krajcberg, he traveled to the north of Mato Grosso, the region of the Juruena and Aripuanã rivers. In this area where a large colonization project is being developed, Cotriguaçu, Sepp documents the progressive destruction of the Amazon rainforest and decides to show these images in large-format drawings on paper.
He exhibited at the Teatro Amazonas in Manaus in 1985, donating the works sold to INPA-Instituto Nacional de Pesquisa da Amazônia, Projeto Peixe-Boi, to help build the Center for Research on Aquatic Mammals.
in 1986 he exhibited "Brasil Natureza Morta" with drawings and photos of fires at Galeria Paulo Figueiredo in São Paulo.
After a brief break in 1987, he began to paint flowers, in a profusion of colors in the most perfect form of exuberance and explosion of life, and held the exhibition entitled "Natureza Viva" at Galeria Múltipla.
On July 17, 1988 he died in São Paulo.