The arrival of the radio in Spain in the first quarter of the twentieth century was reported almost daily by the newspapers, which initially considered the new invention as a technological toy alien to journalism. The first tests of transmission of music and voice alerted the press, who changed their opinion and gave space on its pages to new specialized sections echoing the requests of radio amateurs. In a few years, communication firms saw a business opportunity on the radio and were totally involved in the consolidation of the new mass medium. This article makes a detailed tour through the pages of the Madrid press from 1900 to 1924, analyzing this evolution.