Indium was discovered in 1863, by the physics professor F. Reich and his assistant T. Richter at the Freiburg School of Mines, while they were checking local zinc ores with a spectrograph for thallium. After several attempts, Reich obtained a precipitate that he knew to be a sulfide of an unknown element. He used than several spectrographic techniques to identify the new element. However, Reich, suffering from daltonism, asked for help to his assistant T. Richter, for doing the spectral analysis. Richter observed a bright blue stripe, unknown in any other spectrum and distinct from the blue stripe of cesium. To this new element was given the name indium because of the bright indigo blue spectral stripe.

Metallic indium was first obtained in 1867,by T. Richter.