When Opatija became part of the Kingdom of Italy in 1920 following the Peace Treaty of Rapallo, Jewish people were authorized to establish an independent community. The statute was approved through a decree dated 12 December 1922 (no. IV Culto 44806/2637) by the prefect of Trieste, Francesco Crispo Moncada (1867-1952). In 1923, the Jewish community of Opatija does become the youngest (and smallest) one in Italy. In 1931 it consisted of 80 members.
The Jewish community of Opatija immediately began to look for a permanent place for worship and a rabbi to officiate rites. It was only in 1925, however, that the project was entrusted to two civil engineers, Vittorio Angyal (1889-1952), of Hungarian origins, and Pietro Fabbro, the owners the Rijeka-based Impresa Costruzioni Edili. A few years later they were commissioned to build the synagogue in Rijeka as well. According to the Croatian architectural historian Zlatko Karac, the project was similar in many ways with the Trieste synagogue, although it was more linear in form and less rich in Jewish ornamentation. The Opatija synagogue was to be built in Mandrija Park, in the city centre.
V. Angyal and P. Fabbro, "The project of the Jewish temple for Opatija”, 1926