Gaston Bertrand focuses on interior scenes (the house in Schaerbeek where he lives with his mother). He also paints Nus sur la plage.
In February, Robert Delevoy organizes for him a major individual exhibition at the Apollo Gallery with around fifty works exhibited.
René Lust, future president of the Young Belgian Painting, purchases Figure de femme aux deux personnages, one of the many portraits of the artist’s mother that were painted at that time.

Bertrand deliberately uses neutral colours such as whites, greys and blacks (e.g. Figure de femme aux mains jointes).
He’s awarded the « 1945 Prize» by the Brussels Association Les Amis de l’Art populaire.
At the request of Raymond Gérôme, who was then animator of the Brussels Palace of Fine Arts Theatre, he creates the theatre decor and stage curtain for the adaptation of Rain by Somerset Maugham (April-May).
In May, he is invited to the wedding of his friend Marc Mendelson and paints on this occasion his strange self-portrait Autoportrait au chapeau haut de forme.
On 3 July, he contributes to the creation of the Young Belgian Painting Association by Robert Delevoy and chaired by the lawyer René Lust (the other founding members are: W. Anthoons, R. Barbaix, A. Bonnet, J. Cox, J. Godderis, E. Mahy, M. Mendelson, Ch. Pry, M. Quinet, R Slabbinck and L. Van Lint).
In August, Albert Dasnoy publishes in the Carnets du Séminaire des Arts the first significant article devoted to the artist. Furthermore, Gaston Bertrand is chosen by Louis Van Lint and Marc Mendelson for the first exhibition organized by the Youg Belgian Painting at the Cercle interallié in Ostend.
During a stay in Paris, he discovers the book Poetics of Music by Igor Stravinsky, which is a compilation of a series of lectures that the composer gave in the United States and which consolidated the painter’s aesthetic and ethical stance towards creation.  

For the first time, Gaston Bertrand draws an extensive series of studies on a selected theme (Figure drappée). He paints five self-portraits.
In March and April, he participates, together with Bonnet, Mahy, Mendelson, Mortier, Pry, Quinet and Van Lint, in the Young Belgian Painting exhibition at the Galerie de France in Paris. This gives him the opportunity to make a short stay in Paris.
Second personal exhibition at the Apollo Gallery, which is run by Robert Delevoy. The essay written by Robert Delevoy, La Jeune peinture Belge, and published by the Editions Formes in Brussels devotes an important chapter, entitled “Gaston Bertrand ou l’angoisse du vide” (“Gaston Bertrand or the fear of emptiness”), to the artist (September).
Participation in the exhibitions of the Young Belgian Painting held in The Hague, Amsterdam and Buenos Aires. The main collectors of modern art in Brussels, such as Philippe Dotremont, Gustave Van Geluwe, Willy Grubben, Félix Malisoux, Marcel La Haye, Tony Herbert and Marcel Mabille get interested in Bertrand’s work and purchase his works.

With nine other colleagues, Gaston Bertand is selected by Paul Fierens to participate in the exhibition of the Young Belgian Painting organised in Stockholm in January and February. Due to a dockers’ strike in Antwerp, all the artworks need to be transported by air and René Lust asks Gaston Bertrand and Mig Quinet to accompany him to Stockholm with the shipment. After visiting the Uppsala University, they have a car accident which causes no serious injury to Gaston Bertrand but Mig Quinet and Marc Mendelson must be hospitalized.

Gaston Bertrand attends the masked ball at the Auberge du Lion d’or and the “Bal de la couleur” at the Grand Duchy Hall, two parties organized in Brussels for the benefit of the Young Belgian Painting. Gaston Bertrand illustrates with drawings the second edition of the magazine bruxelloiseFestival. He makes his first completely non-figurative drawings based on plane geometry. With the Portrait du Comte Philippe d’Arschot, an art critic who promoted Bertrand’s work, he starts the series of commissioned stylized portraits, which are a synthesis of studies drawn from nature.
Significant participation in the major Young Belgian Painting exhibition held at the Palace of Fine Arts in Brussels in October and November.

Robert Giron requests the participation of Gaston Bertrand in an exhibition showing Belgian artists’ gouaches and drawings (with Brusselmans, Tytgat, Magritte, Delvaux, Van Lint, Mendelson and Cox) and which was held at the Brooklyn Museum of New York.
Bertrand visits Paul Klee’s retrospective exhibition held at the Palace of Fine Arts of Brussels (March).
He participates in the 14th Venice Biennale as part of the Young Belgian Painting.
During the summer, he stays in Coxyde with Betty and produces 87 watercolours inspired by the dunes and the shore. This work leads him to undertake more abstract researches.
In his book, La Peinture moderne, the Italian art historian Lionello Venturi notes that Gaston Bertrand is one of the most powerful character among the Belgian artists of his generation.

Stays in Ostend and then in Ault and Onival (in the Somme, North of France) where the landscapes inspire him many drawings and watercolours as well as some oil paintings. The watercolours Géométries are his first truly abstract coloured works.
Bertrand participates in the “15th International watercolours biennial” held at the Brooklyn Museum of New York (he produces 82 watercolours during that year).
Gaston Bertrand takes charge of the practical organization of the Belgian participation (Bertrand, Mendelson, Scauflaire, Tytgat and Van Lint) in the Salon des Tuileries, which is held that year at the Charpentier Gallery in Paris.  On this occasion, he spent the month of October in the French capital.

At the request made in 1949 by Canon Lanotte (in charge of the architectural and aesthetic developments for the religious buildings administered by the Namur bishopric), Bertrand creates a series of designs for stained glasses (Le royaume de Dieu) which appear to be, in the field of religious art, the first abstract proposal produced in post-war Belgium.
He is invited to the “Salon de Mai” in Paris, where he was regularly invited from then on.
He produces a series of drawings during a trip to Koudekerke on the Dutch coast.
First purchase of an art piece by the Royal Museums for Fine Arts of Belgium: Architecture, a painting that he had made in 1949.

Gaston Bertrand is deeply affected by the death of his mother on 27 September and draws a series of moving drawings representing her on her deathbed.
He produces a dozen paintings, all very architectural and in which the themes represented in La cathédrale, La ville et La cité can be found.
He builds a house-studio at 151 Aubépines Avenue in Uccle (Brussels) according to the plans of the architect Jacques Dupuis, which perfectly match with his own aesthetic ambitions.

Bertrand and Betty get friends with the banker Bénédict Goldschmidt and his wife Alla, who are soon portrayed by the artist and buy a number of his works.

At the invitation of Emile Langui, Gaston Bertrand participates in the 1st São Paulo Biennial and shows three paintings that he had made in 1951 : Le hangar, Composition aux triangles blancs and Peinture.
On 9 March, He moves with Betty into their new house. He paints Les grandes orgues as well as his two first commissioned portraits of women (Alla Goldschmidt, Mrs. Solvay).

The Museum of Modern Art of Rio de Janeiro purchases the painting Scène au miroir (painted in 1949). At the invitation of Robert Giron, the Palace of Fine Arts of Brussels organizes the first major retrospective exhibition dedicated to his work (seventy-one works are exhibited) with the introduction to the catalogue written by Paul Fierens.
First purchase of an artwork (Vers une quatrième dimension I) by the Royal Museum of Fine Arts of Antwerp.
Participation in an international drawing exhibition at the Chicago Art Institute.
With some former members of the Young Belgian Painting, architects, engineers and a few art historians, Gaston Bertrand co-founds the Espace group, an association aiming to “contribute to the harmonious development of human activities through plastic representation” (the group was short-lived). Gaston Bertrand is invited by the APIAW (Association for the intellectual and artistic progress of Wallonia) for a personal exhibition held in Liège (introduction to the catalogue written by Robert Delevoy). Gaston Bertrand explores the theme of Vers une quatrième dimension in two paintings and one watercolour. He also paints Invention de l’homme, Jeux de plage, Composition pour un mur and Parallèles.

Under the auspices of the Embassy of Belgium in the United States, Bertrand’s work is exhibited at the Stable Gallery in New York, which is his first individual exhibition abroad.
In Paris, the art critic Léon Degand devotes an article to the artist in the March issue of the magazine Art d’Aujourd’hui.
Stay in France.
After obtaining a grant from the Belgian State, he undertakes a long trip to Italy in November and December and visits the cities of Milan, Florence, Rome (where he stays at the Academia Belgica), Anzio, Bologna and Siena.

He is inspired by the architecture of these cities, particularly by the burial chapel of the Medicis designed by Michelangelo in Florence.
After this trip to Italy, the painter departs from his monochrome palette and softens the rigorously abstract compositions that previously characterized his work up to then.  

Bertrand participates again in the 2nd São Paulo Biennial and wins the first purchase prize as well as a 30,000 cruzeiros grant.
The Belgian art critics’ Association awards the annual grand critic’s prize to Gaston Bertrand for the 1952-1953 season. The artist wins by taking fourteen votes compared to only three for Poliakoff (the Belgian artists Cobbaert, Delhez and Mortier and the French artists Zadkine and Schneider were also competing). Under the aegis of the Ministry of public instruction, Robert Delevoy writes the first study devoted to the painter as part of the artists’ monographs published by the Belgian State.

In April, he travels to the Costa Brava and stays in Palamos. His drawings of the city and its surroundings lead to a series of watercolours and oil paintings (Bellcaire).
Following the request made by Canon Lanotte in 1951 regarding the re-design of the Sainte-Julienne Church in Salzinnes and the creation of two frescos, Gaston Bertrand gets on with researches on the themes of La Religieuse and la Trinité.
A monograph written in Dutch by Jan Walravens is devoted to the artist.
The Sao Paulo Museum of Contemporary Art acquires a large work painted in 1952 and entitled Composition. In 1960, the Museum also purchases the watercolour Firenze painted in 1954.
Inspired by Italy and Spain, Gaston Bertrand paints 22 oil paintings, including Peinture froide, Trinita dei Monti, Rome bleue and Siena as well as 27 watercolours.

Luc Haesaerts gives a conference on Gaston Bertrand at the Royal Museums of Fine Arts in Brussels (6 March).
The Il Milione Gallery in Milan organizes an exhibition of his works.
At the request of the poet and art critic Jacques Meuris, Gaston Bertrand illustrates a poetic collection entitled Les paysages immobiles with four abstract dry point engravings. Following that experience, the artist engraves several dry points. Gaston Bertrand is invited to participate in an international contemporary painting exhibition at the Carnegie Institute of Pittsburgh, which purchases the watercolour Caprarola (painted in 1953).
The Parisian editor Michel Brient publishes, as part of the collection “Artistes de ce Temps”, a short monograph devoted to the painter and written by Robert Delevoy.

Gaston Bertrand, as well as six other Belgian artists, is chosen by the Shell oil company to create a painting inspired by its petroleum sites. This experience gives rise to a dozen watercolours and some oil paintings.
During the autumn, Bertrand stays in Alassio, next to San Remo, and paints seven watercolours.Among the 22 paintings produced that year, particularly notable ones are Notation musicale (purchased by the Chase Manhattan Bank), Vert bleu gris (Gaston Bertrand Foundation) and Hommage à Michel-Ange (later purchased by the Royal Museums of Fine Arts of Belgium).

In Paris, Bertrand exhibits for the first time Paysages immobiles at the gallery-bookshop La Hune as well as around twenty recent paintings at the gallery La Roue. Jeanne Bucher acquires the painting Pour un hommage à Michel-Ange II.
During that stay in Paris, Gaston Bertrand feels for the first time attracted to the Paris subway and takes some notations on that theme.

Jean Giraud, professor at the Saint-Luc Superior School in Saint-Gilles (Brussels), asks him to lead the school’s advanced painting workshop. In this workshop, Bertrand is the teacher of some young promising painters, including Luc Mondry, Boris Semenoff, Camille De taeye and Francis De Bolle, with a pedagogical approach derived from his own aesthetic ambition.