V.P.Goncalves,F.S.Navarra and D.Spiering Exclusive processes wit ha leading neutron in ep collisions Abstract In this paper we extend the colour dipole formalism to the study of exclusive processes associated with a leading neutron in ep collisions at high energies. The exclusive $\rho, \phi$ and $J/\psi$ production, as well as the Deeply Virtual Compton Scattering, are analysed assuming a diffractive interaction between colour dipole and the pion emitted by the incident proton. We compare our predictions with the HERA data on $\rho$ production and estimate the magnitud of the absorption corrections. We show that the colour dipole formalism is able to describe the current data. Finally, we present our estimate for the exclusive cross sections which can be studied at HERA and in future electron-proton colliders. LU TP 15-59