  Borexino is a liquid scintillation detector located deep underground at the
Laboratori Nazionali del Gran Sasso (LNGS, Italy). Thanks to the unmatched
radio-purity of the scintillator, and to the well understood detector response
at low energy, a new limit on the stability of the electron for decay into a
neutrino and a single mono-energetic photon was obtained. This new bound, tau >
6.6 10**28 yr at 90 % C.L., is two orders of magnitude better than the previous
limit.
