In the elections of June 1931 to cuts constituents of the second Spanish Republic is elected by Almeria. Also it would be elected in the elections of 1936. The military rebellion of general Franco was surprised with his family in Rioja, Almeria. Organizes an antifascist Central Committee, with all the forces of the left, to prevent the triumph of the military uprising in Almeria and manages with the Minister of the Navy, the gunboat Lepanto return to the port of Almeria, which meant the performance of the rebels. Shortly afterwards was appointed Commissioner of the battleship Jaime I, in him was, when in June 1937, the terrible explosion in which there were numerous deaths occurred. Commissar of war and, later, Chief of the commandery of engineering of Barcelona was later appointed. He continued as Deputy attending the sessions of cuts that took place in Barcelona and was one of the members who participated on 1 February 1939, in the castle of Sant Ferran de Figueres, which would be the last session of the Cortes of the second Republic in Spanish territory.

On February 6, 1939 Pradal embarks on the path of exile across the Spanish-French border, with his two older children. His wife and their three children had remained during the war in Rioja, embarked in the port of Alicante on a British ship bound for Algeria, and after passing through the field of Carnot, could meet in July with the rest of the family in France, which established his residence in Toulouse. Wasn’t you, professionally supporting their stay in France, where very little could do with its proven competence of architect because was not recognized the title. Once France was occupied by Nazi troops, the Francoist Government condemned him to three death sentences and asked for its extradiccion. He was arrested but not returned to Spain, other Yes detainees were taken to Spain and killed: as Julian Zugazagoitia, director of the Socialist of Madrid and Minister of the Interior with Negrin, Francisco Cruz left, editor of the same newspaper, trade unionist Juan Peiro, Minister with Largo Caballero, and Luis Companys, President of the Generalitat and one of the founders of Esquerra Republicana de Catalunya.