Carbon monophosphide is a diatomic chemical with formula CP.

It is a heavier analog of the cyanide radical (CN).

CP and CN are both open-shell species with doublet Π ground electronic states while the ground states of CS and CO are closed-shell.

The related anion, CP−, is called cyaphide and isoelectronic with CS.

Carbon monophosphide was detected in the circumstellar envelope of the star IRC +10216 in 1990,[1] observed with the IRAM 30m radiotelescope.