  The LENA (Low Energy Neutrino Astronomy) detector is proposed to be a
large-volume liquid-scintillator device which will be highly suitable for the
investigation of a variety of topics in astrophysics, geophysics and particle
physics. In this paper, the potential of such a detector concerning the search
for proton decay in the SUSY favored decay channel p->K+antineutrino is
investigated. Based on Geant4, Monte Carlo simulations of the proton decay in
the LENA detector as well as of the background radiation in the detection
energy windows have been developed. From these simulations an efficiency of 65%
for the detection of a possible proton decay has been determined. Within ten
years of measuring time a lower limit for the proton lifetime, concerning the
decay channel investigated, of tau>4.10^{34} y could be reached.
