Chromium(II) oxide (CrO) is an inorganic compound composed of chromium and oxygen.

[1] It is a black powder that crystallises in the rock salt structure.

CrO is basic, while CrO3 is acidic, and Cr2O3 is amphoteric.

[3] CrO occurs in the spectra of luminous red novae, which occur when two stars collide.

It is not known why red novae are the only objects that feature this molecule; one possible explanation is an as-yet-unknown nucleosynthesis process.