  Comets are important "eyewitnesses" of Solar System formation and evolution.
Important tests to determine the chemical composition and to study the physical
processes in cometary nuclei and coma need data in the UV range of the
electromagnetic spectrum. Comprehensive and complete studies require for
additional ground-based observations and in-situ experiments. We briefly review
observations of comets in the ultraviolet (UV) and discuss the prospects of UV
observations of comets and exocomets with space-born instruments. A special
refer is made to the World Space Observatory-Ultraviolet (WSO-UV) project.
