Hydrogen incorporation into lithium niobate and lithium tantalate during crystal growth has attracted research interest for a long time, but the diffusion paths and defect sites within the materials are only partially understood. The impurities highly influence the properties of the material and often form the basis for important applications. Therefore, the underlying ionic migration processes not only of hydrogen are of high scientific interest, but those of lithium and oxygen as well. For these ionic species a complete set of kinetic parameters, such as diffusion barrier and diffusion coefficient, are not yet available. Consequently, we propose lattice dynamic measurements and determination of thermally activated ionic transport pathways via temperature dependent inelastic and quasi-elastic neutron scattering.