  We investigate a single scalar neutrino production at the upgraded HERA with
high luminosity in the framework of an R-parityviolating supersymmetric model.
We find that the scalar neutrino with mass around 100GeV could be observed
through investigating the multilepton production process e- p -> mu-
sneutrino(tau) X -> mu- (e- mu+) X. The signal would be characterized by mu+
and e- with high transverse momentum as well as a sharp peak in the invariant
mass M(e-,mu+) distribution.
