Orlando Ribeiro is admitted as a reader of Portuguese at the Sorbonne, University of Paris, on invitation of the Instituto de Alta Cultura.
During this period he studies Geography at the Faculty of Arts of the same university, at the École Normale Supérieure and at the Collège de France. He travels to various parts of France, under the orientation of several professors - Emmanuel de Martonne, Albert Demangeon, Luteaud, Marres and Sion. The influence of de Martonne, professor of Physical Geography, was decisive for Orlando Ribeiro.
He takes part in the Seminar on Geography and Geology of the University of Liège (Belgium). With Macar and Dussart, two of the assistant-professors, he studied the morphological problems of the Ardennes border and the terraces of the river Mosa.
He starts a study on the Beira Baixa region, applying the methods of the modern Geography.
Orlando Ribeiro attends the 15th International Congress of Geography, in Amsterdam, as a delegate of the Portuguese government, on behalf of the Instituto de Alta Cultura. Under his initiative, the International Geographical Union asks the Portuguese government to host its next congress in Lisbon.
Orlando collaborates with Professor de Martonne in the organization of the practical works of the Geography course, giving classes and directing excursions to the Paris environs.
He also participates in the summer courses organized by the University of Coimbra.
Two weeks before the occupation of France by the German, Orlando Ribeiro returns to Portugal.
Orlando is admitted as a Professor at the Faculty of Arts of the University of Coimbra. At the time, major names in several areas of his interest were teaching there, such as Paulo Merêa, Pierre David, Virgílio Correia, Joaquim de Carvalho, Paiva Boléo, Paulo Quintela, Amorim Girão and Fernandes Martins.
Orlando Ribeiro is appointed Full Professor in the Faculty of Arts, University of Lisbon. Among the Assistant-professors of the time at that faculty were António José Saraiva e Vitorino Magalhães Godinho.
In the same year, he founds the Centro de Estudos Geográficos de Lisboa, upon request of the Instituto de Alta Cultura.
As it was difficult to travel abroad because of the War, Orlando Ribeiro concentrates in studies and travelling in Portugal.
Portugal, o Mediterrâneo e o Atlântico, Coimbra Editora, Coimbra, is published.
(Other editions: illustrated with photographs by Jorge Barros, Edições João Sá da Costa, 1993; 7th ed., Lisboa, Livraria Sá da Costa Editora, 1998).
Travel to Guinea, in a mission to prepare the Segunda Conferência Internacional dos Africanistas Ocidentais that would take place in Bissau.
Orlando Ribeiro organizes in Lisbon The 16th International Congress of Geography, the first after the end of the War. Four volumes of proceedings and the guide-books of six scientific excursions were published. He authored two of these guidebooks, one about the central region of Portugal, the other about the Madeira Island.
Le Portugal Central, UGI, Lisbonne (2nd edition in 1982).
L' Île de Madère. Etude Géographìque,
(Portuguese edition: A Ilha da Madeira até Meados do Século XX, Lisboa, ICALP, 1988).
At the end of the Congress, he was appointed Vice-President of the International Geographical Union (IGU). In the following Congress, held in Washington in 1952, he was appointed first Vice-President of the same organization.