This article is for the sound-on-film technology. For the telecommunication device invented by Alexander Graham Bell and Charles Sumner Tainter, see Photophone.

RCA Photophone was the trade name given to one of four major competing technologies that emerged in the American film industry in the late 1920s for synchronizing electrically recorded audio to a motion picture image. RCA Photophone was an optical sound, "variable-area" film exposure system, in which the modulated area (width) corresponded to the waveform of the audio signal. The three other major technologies were the Warner Bros. Vitaphone sound-on-disc system, as well as two "variable-density" sound-on-film systems, Lee De Forest's Phonofilm, and Fox-Case's Movietone.