This paper seeks to explore the role of a new form of communication in fostering transnational Islamic identities in the mid-20th century. From the late 19th-century onward, the development of the press and the influence of key reformist journals such as al-‘Urwa al-Wuthqa in Paris, al-Manar in Egypt and al-Basa’ir in Algeria, generated greater awareness of Muslim interconnectedness across borders. This phenomenon may be seen as a prelude to what Olivier Roy has referred to as “the globalization of Islam.” Yet the impact of the press remained confined primarily to elite circles. In societies where literacy rates were limited, this proved to be a major impediment to the spread of reformist ideas. My paper argues that by the mid-1930s, Muslim reformers understood the potential of shortwave radio as a new technology capable of breaking the barrier of illiteracy and bringing their reformist message to a greater number of Muslims worldwide. This, in turn, nurtured these reformers’ tendency to think in transnational terms and to articulate an Islamic discourse valid for all Muslims everywhere, regardless of local conditions. Hence, this paper focuses on the epistemological rather than ideological significance of shortwave radio in the history of modern Islamic thought. Radio-Berlin—an Arabic-language station sponsored by the Nazis—was not merely as a crucible where elements of Nazism and Islamism came together, as the work of Jeffrey Herf suggests; it was also a medium that encouraged and facilitated the standardization of Islam and Islamic activism in the mid-20th century. To substantiate this claim, I use the experiences of Taqi al-Din al-Hilali, a Moroccan exile and Salafi activist in Nazi Germany between 1936 and 1942, whose fascination for shortwave radio and collaboration with Radio-Berlin is documented. His story sheds light on the motivations and ideas of one of these “generally anonymous native Arabic-speaking announcers and writers” (Herf, Nazi Propaganda for the Arab World, pp. 8-9) that Herf’s recent book does not examine. My paper revolves around three main questions: How did al-Hilali explain his fascination for shortwave radio? As a radio announcer, what could he do to further the Islamic reformist cause (as he understood it)? How did his experience at Radio-Berlin impact the rest of his career as an Islamic activist? Sources for this paper include relevant journal articles written by al-Hilali in the 1930s, al-Hilali’s memoirs, and French archival materials pertaining to the diffusion of Radio-Berlin in North Africa.