He studied art at the Hoyos Painting Academy and the Cercle Artístic de Sant Lluc in Barcelona.
[2] He also published comics and cartoons in L'Esquella de la Torratxa, El Senyor Canons, Mirador, and many other magazines.
His cartoons in favor of the allied cause in World War I were collected in the book Kameraden, and earned him the Cross of the Legion of Honor.
He developed an important work as an artistic critic, under the pseudonym "Joan Sacs", writing articles in the Catalan press and several books.
The Spanish critic Juan Manuel Bonet has compared Eliu's work to that of the German New Objectivity movement, and termed him "in a way, our Félix Vallotton".