  We calculated bulk viscosity due to non-equilibrium weak processes in
superfluid nucleon-hyperon matter of neutron stars. For that, the dissipative
relativistic hydrodynamics, formulated in paper [1] for superfluid mixtures,
was extended to the case when both nucleons and hyperons are superfluid. It was
demonstrated that in the most general case (when neutrons, protons, Lambda, and
Sigma^{-} hyperons are superfluid), non-equilibrium weak processes generate
sixteen bulk viscosity coefficients, with only three of them being independent.
In addition, we corrected an inaccuracy in a widely used formula for the bulk
viscosity of non-superfluid nucleon-hyperon matter.
