Using a parallel plate rheometer equipped with a partitioned plate, and an extensional fixture (SER), a full rheological characterization of several commercial ionomers has been carried out including the determination of the linear viscoelastic moduli, the damping function and the tensile stress growth coefficient. The experimental rheological data have been fitted to a viscoelastic model (the K-BKZ model). Particular emphasis has been placed on the distribution of the relaxation times to identify the characteristics times such as reptation, Rouse, and sticky-Rouse that is associated with the characteristic life time of the ionic associations. The effect of ionic association on the rheological behavior was studied by comparing the properties of ethylene methacrylic acid copolymer with the corresponding ionomers neutralized with sodium hydroxide. Furthermore the processing (melt fracture performance) of these polymers was evaluated by means of a capillary rheometry and critical correlations were derived between molecular characteristics/relaxation times and the critical shear stresses for the onset of melt fracture.