[en] We report observations of rotational transitions of SiO in the ground vibrational state at 86.8 GHz (J=2→1) and 130.3 GHz (J=3→2). At 86.8 GHz, SiO emission in Orion A peaks in the direction of the Kleinmann-Low nebula. A possible secondary maximum occurs about 80'' southward. The 130.3 GHz line was also detected in Orion A. Mapping of the 86.8 GHz line in Sgr B2 shows the presence of two velocity components and a north-south extent of about 4'. Comparison of the data with radiative-transport calculations implies that if the hydrogen density is approximately 10⁵ cm^-3 then the SiO column density is approximately 10¹⁵ cm^-2 for Orion A at 60 K.Upper limits to the total HO₂ column density in Orion A and Sgr B2 are reported