  We propose a possible explanation for the recent claim of an excess at 3.5
keV in the X-ray spectrum within a minimal extension of the standard model that
explains dark matter and baryon abundance of the universe. The dark matter mass
in this model is ${\cal O}({\rm GeV})$ and its relic density has a non-thermal
origin. The model includes two colored scalars of ${\cal O}({\rm TeV})$ mass
($X_{1,2}$), and two singlet fermions that are almost degenerate in mass with
the proton ($N_{1,2}$). The heavier fermion $N_2$ undergoes radiative decay to
the lighter one $N_1$ that is absolutely stable. Radiative decay with a life
time $\sim 10^{23}$ seconds can account for the claimed 3.5 keV line, which
requires couplings $\sim 10^{-3}-10^{-1}$ between $X_{1,2}, ~ N_{1,2}$ and the
up-type quarks. The model also gives rise to potentially detectable monojet,
dijet, and monotop signals at the LHC.
