  Quantum decoherence, the evolution of pure states into mixed states, may be a
feature of quantum-gravity models. In most cases, such models lead to fewer
neutrinos of all active flavours being detected in a long baseline experiment
as compared to three-flavour standard neutrino oscillations. We discuss the
potential of the CNGS and J-PARC beams in constraining models of
quantum-gravity induced decoherence using neutrino oscillations as a probe. We
use as much as possible model-independent parameterizations, even though they
are motivated by specific microscopic models, for fits to the expected
experimental data which yield bounds on quantum-gravity decoherence parameters.
