The aim of the work is to characterize by quasielastic neutron scattering (QNS) not only the usual transport processes occurring in aqueous solution but also something specific to the high proton conductivity in acidic solutions. The addition of a strong acid such as H2SO4 or HNO3 to water provokes a marked slowing down of the mean translational diffusive motions and, to a lesser extent, of the rotational ones. Furthermore, the authors have evidenced a weak and broad additional QNS component which is not present in pure water. However, the presence of this component also in concentrated salt solutions eliminates the hypothesis of a fast proton transport process and indicates that some kind of relaxation process of the ionic environment could be involved.