Ultra-fast High-temperature Sintering (UHS) is a novel sintering method which enables rapid densification of ceramic materials within seconds. For conducting UHS cycles, green compacts are placed between thin strips of carbon felt, which are heated with extremely high rates up to 10⁵ °C/min by resistance heating (Joule heating). The process is mainly controlled by limiting maximum current and dwell time. Using strontium titanate and 2 mol. % iron doped strontium titanate as model materials, a systematic parameter study was done targeting on to investigate the influence of the applied current on degree of densification and resulting grain size. For both materials, rapid densification in context of extremely high heating rates was demonstrated. In the case of undoped strontium titanate, exaggerated grain growth in combination with formation of isolated pores was observed. The addition of 2 mol. % iron was found to be beneficial for limiting the grain growth and therefore enabling more uniform densification and grain growth. Elemental segregation at grain boundaries was analysed by scanning transmission electron microscopy/energy disperse x-ray spectroscopy (STEM/EDS). Impedance spectroscopy was used to measure the electrical conductivity of both materials. When comparing the conductivity of UHS sintered and conventionally sintered samples, no remarkable difference was observed.