This paper presents the reactions which can be performed at COMPASS to study
the Generalized Parton Distributions (GPDs). The high energy muon beam at CERN
allows to measure Hard Exclusive Meson Production or Deeply Virtual Compton
Scattering (DVCS) in the Bjorken regime in a large range of Q^2 and x_Bj
(1.5<Q^2<7.5 GeV^2 and 0.03<x_Bj<0.25). Exploratory measurements dedicated to
rho_0 or pi_0 production can be investigated with the present setup. DVCS
measurement require an upgrade of the COMPASS setup.Comment: 20 pages, 9 figure
