Radio-Activity is Kraftwerk's first entirely electronic album, conceptually organized around the themes of radioactive decay and radio communication. The hyphenated album title displays Kraftwerk's typical deadpan humour, being a pun on the twin themes of the songs, half being about radioactivity and the other half about activity on the radio.
It was the first Kraftwerk album to feature use of the distinctive Vako Orchestron keyboard (choir, string and organ sounds), which the group had purchased on their recent US Autobahn tour and the Moog Micromoog which was used extensively on this album. Notably, it provided the harsh sounds on the track "Antenna". The band's custom-built electronic percussion also featured heavily in the sound, and extensive use was made of the vocoder. The usual synthesizers were present, and Hütter's Farfisa electronic piano made a return on "Transistor". For the first time the group did not use flute, violin or guitars.