  We present some R-parity conserving supersymmetric models which can
accommodate the 3.5 keV X-ray line reported in recent spectral studies of the
Perseus galaxy cluster and the Andromeda galaxy. Within the Minimal
Supersymmetric Standard Model (MSSM) framework, the dark matter (DM) gravitino
(or the axino) with mass of around 7 keV decays into a massless neutralino
(bino) and a photon with lifetime ~10^{28} sec. The massless bino contributes
to the effective number of neutrino species N_eff and future data will test
this prediction. In the context of NMSSM, we first consider scenarios where the
bino is massless and the singlino mass is around 7 keV. We also consider
quasi-degenerate bino-singlino scenarios where the mass scale of DM particles
are O(GeV) or larger. In such a scenario we require the mass gap to generate
the 3.5 keV line. We comment on the possibility of a 7 keV singlino decaying
via R parity violating couplings while all other neutralinos are heavy.
