High-voltage cables with paper-oil based insulation are still widely used in electric power systems. One issue with EMTP-type modeling and simulation of such cables is that the permittivity of the insulation is frequency-dependent, thereby contributing to the dispersion of traveling waves. This frequency dependency is not taken into account in currently available EMTP-type programs. This paper presents field measurements from step voltage excitations on three different oil-filled cables with steel armoring. The waveforms are compared to EMTP-type simulations, demonstrating significant deviations from the measured waveforms. The frequency-dependency of the permittivity is next taken into account using a formula obtained by Breien and Johansen, and the modeling and simulation procedure is repeated. Inclusion of the frequency-dependency is shown to bring the simulation results much closer to the measured waveforms. © 2014 Elsevier B.V. All rights reserved.