Initially observed in 1971, the diatomic species SiO was the first of half a dozen molecules containing silicon to be detected in space. A single radio emission line line for SiO was reported by Wilson et al. toward Sgr B2. A second, confirming line was subsequently detected by Dickinson toward both Sgr B2 and Orion A. Both sets of observations were made using the 36 foot (12 meter) radio telescope Kitt Peak National Observatory. This instrument was closed down in 2000 after more than three decades of operation that helped to establish molecular astronomy. Glycoaldehyde was one of the last molecules to be discovered with the 12m telescope.

Recent experiments have shown that stardust can form from the condensation of simple diatomic SiO.

The bonding in SiO resembles that of SiS.