The last important center of Dadaist activity in Germany was Köln between 1918 and 1922. Like the Berliners, Max Ernst and Theodor Baargeld (the latter highly influenced by Picabia), joined by Hans Arp in 1919, made themselves known in the city by stirring up controversies, publishing reviews (Der Ventilator, Die Schammade), and organizing one particular exhibition that was quickly closed by the occupation authorities. Working together, Arp and Ernst did collages they called "Fatagaga," an abbreviation for "fabrication de tableaux garantis gazométriques" (manufacture of pictures guaranteed to be gasometric); an example is Physiomythologisches diluvialbild (1920, Hannover, Brusberg Gallery), realized using the photomontage technique. During this period, Ernst, also very influenced by Giorgio de Chirico, produced several of his best works by combining different techniques of collage. In 1 Kupferblech 1 Zinkblech 1 Gummituch 2 Tastzirkel... (circa 1920, work missing), the artist piece together fantastic figures using pictures of various objects (goggles, a retort, pipes...) he had cut out of printed matter, then completed his composition with traditional watercolor and drawing. The Little Lacrimal Fistula that Says Tick Tock (1920, New York, The Museum of Modern Art) is made of braided strips of wallpaper transfigured into a monumental wall. In Max Ernst's works, the title cannot be dissociated from the image (it is, moreover, as in Paul Klee and Kurt Schwitters, usually inscribed on the work itself). It confers a mysterious, poetic meaning on the composition, which is always, if not figurative, at least allusive. Ernst's works testify to a great variety of inspirations (e.g., Dada Degas by Dada Max Ernst the Knitter, Paris, formerly in the collection of Louis Aragon). By systematically bringing together elements taken out of their original context, Ernst was able to create new visions of reality, based - often humorously - on incongruity, paradox, and the uncanny. In 1921, he began experimenting with a new kind of collage using, as a point of departure, 19th-century illustrations, mostly woodcuts, taken from such publications as Le Magasin pittoresque and L'Illustration. The artist would cut out certain parts of these illustrations and insert them into new compositions so carefully that it is quite difficult to detect the montage. The resultant images are perfectly homogeneous, as in The Preperation of Bone Glue (1921, Paris, formerly in the Galerie François Petit). During his Surrealist period, Ernst further developed this technique in his famous books of plates La Femme 100 Têtes (1929) and Une semaine de bonté (1934).

A group of artists including Anton Räderscheidt, Franz-Wilhelm Seiwert, and Angelika Hoerle formed in Köln at this time. But Arp went to Paris in 1920, and Ernst followed in 1922.