This study is an investigation of the infrared properties of SiO in the wave‐length range 1 to 30 μ‐ The samples used in this study consisted of the commercially available bulk silicon monox and thin films made by evaporating this bulk material. Films which were made by evaporating onto a silicon substrate were used for transmission measurements. Reflectivity measurements as well as transmission measurements were made with the bulk material. From the foregoing data it was concluded that, although the bulk material is not SiO but rather a stoichiometric mixture of Si and SiO2, the evaporated films are a true amorphous SiO p