In the past, matrix isolation technique proved to be a proper method to generate new species by oxidation and reduction of the high-temperature molecule SiO. In each case the variation of the SiO multiple bonding was of central interest. During the reduction of SiO with different metal atoms M, different MSiO intermediates result. The co-condensation of Al atoms with SiO ends up with a linear AlOSi radical, which represents the first example of a metal coordination via the O atom of SiO. The structural data based on IR- and Raman spectra are confirmed by quantum chemical calculations. Bonding of AlOSi is similar to that of the high-temperature molecule AlOAl; however, an additional electron is present in the lowest antibonding Pi-orbital.