Galeries Dalmau was an art gallery in Barcelona, Catalonia, Spain, from 1906 to 1930 (also known as Sala Dalmau, Les Galeries Dalmau, Galería Dalmau, and Galeries J. Dalmau). The gallery was founded and managed by the Symbolist painter and restorer Josep Dalmau i Rafel [ca]. The aim was to promote, import and export avant-garde artistic talent. Dalmau is credited for having launched avant-garde art in Spain.

In 1912, Galeries Dalmau presented the first declared group exhibition of Cubism worldwide, with a controversial showing by Jean Metzinger, Albert Gleizes, Juan Gris, Marie Laurencin and Marcel Duchamp. The gallery featured pioneering exhibitions which included Fauvism, Orphism, De Stijl, and abstract art with Henri Matisse, Francis Picabia, and Pablo Picasso, in both collective and solo exhibitions. Dalmau published the Dadaist review 391 created by Picabia, and gave support to Troços by Josep Maria Junoy i Muns [ca].

Dalmau was the first gallery in Spain to exhibit works by Juan Gris, the first to host solo exhibitions of works by Albert Gleizes, Francis Picabia, Joan Miró, Salvador Dalí and Angel Planells. It was also the first gallery to exhibit Vibrationism.

The gallery presented native pre-avant-garde artists, tendencies and manifestations new to the Catalan art scene, while also exporting Catalan art abroad, through exhibition-exchange projects, such as promoting the first exhibition by Joan Miró in Paris (1921). Aware of the difficulty and marginality of the innovative art sectors, their cultural diffusion, and promotion criterion beyond any stylistic formula, Dalmau made these experiences the center of the gallery's programming. Dalmau is credited for having introduced avant-garde art to the Iberian Peninsula. Due to Dalmau's activities and exhibitions at the gallery, Barcelona became an important international center for innovative and experimental ideas and methods.

Born in Manresa, 1867, Josep Dalmau early on devoted himself to painting. In 1884, he moved to Barcelona where he discovered the Modernisme painter Joan Brull. Dalmau's painting were included in several salon exhibitions in Catalonia. In 1899 (8–28 July) he was given his first and only solo exhibition, at Els Quatre Gats, a popular meeting place for artists throughout the modernist period. He continued exhibiting his works throughout his lifetime.

At the age of thirty, he emigrated to Paris where he lived for six years, and studied painting conservation in Bruges and Gant, Belgium.

In 1906, after having finished his studies in restoration, Dalmau returned to Barcelona. He worked as a technical restorer for Museu de Barcelona. In 1914 he restored the complex work of Marià Fortuny, The Battle of Tetuan, 1862–1864. In 1915 he restored the altarpieces for the Board of Museums, known as Junta de Museus de Catalunya.

Dalmau opened an antiques gallery in 1906, Carrer del Pi, 10, becoming his first showroom, lasting from 1906 to 1911. The establishment basically dealt with antique objects, and later extended with a section of modern art. The first documented exhibition of modern art was in 1908, with the exhibition by Josep Mompou i Dencausse and some Japanese prints. The following year Dalmau hosted a joint exhibition of Joan Colom i Agustí, and Isidre Nonell. Dalmau is largely credited for having introduced avant-garde art to Barcelona, and more generally, to Spain. His exhibitions, while promoting international artists, connected Catalan artists with the world of art outside of Spain.