Production of interstellar hydrogen peroxide (H2O2) on the surface of
  dust grains
  Context. The formation of water on the dust grains in the interstellar medium
may proceed with hydrogen peroxide (H2O2) as an intermediate. Recently
gas-phase H2O2 has been detected in {\rho} Oph A with an abundance of ~1E-10
relative to H2.
  Aims. We aim to reproduce the observed abundance of H2O2 and other species
detected in {\rho} Oph A quantitatively.
  Methods. We make use of a chemical network which includes gas phase reactions
as well as processes on the grains; desorption from the grain surface through
chemical reaction is also included. We run the model for a range of physical
parameters.
  Results. The abundance of H2O2 can be best reproduced at ~6E5 yr, which is
close to the dynamical age of {\rho} Oph A. The abundances of other species
such as H2CO, CH3OH, and O2 can be reasonably reproduced also at this time. In
the early time the gas-phase abundance of H2O2 can be much higher than the
current detected value. We predict a gas phase abundance of O2H at the same
order of magnitude as H2O2, and an abundance of the order 1E-8 for gas phase
water in {\rho} Oph A. A few other species of interest are also discussed.
  Conclusions. We demonstrate that H2O2 can be produced on the dust grains and
released into the gas phase through non-thermal desorption via surface
exothermic reactions. The H2O2 molecule on the grain is an important
intermediate in the formation of water. The fact that H2O2 is over-produced in
the gas phase for a range of physical conditions suggests that its destruction
channel in the current gas phase network may be incomplete.
