In the present work, we show how exposure to electricfieldsduring a high-temperature treatment can be used to manipulate surfaceproperties of donor-doped ceramics and thus improve their reactivity. La$_0.1$Sr$_0.9$TiO$_3$(LSTO) nanoparticles, prepared by hydrothermal synthesis,were consolidated under air with and without external electricfields. Althoughneither approaches caused grain growth upon consolidation, the treatmentunder the influence of the electricfield (i.e.,flash sintering) remarkablyenhanced the segregation of Sr on the material’s surface. In addition, a highconcentration of O$^−$defects both in bulk as well as on the material surface wasdemonstrated by spectroscopic methods. This enhanced defect concentrationalong with the nanoscopic grain size of thefield-consolidated materials isprobably one of the triggering factors of their improved charge carriermobility, as observed by impedance spectroscopy. The effect of such aperturbed defect structure on the reactivity of the materials was evaluated by the total oxidation of methane. For materialstreated under the influence of electricfields, the catalytic reaction rate improved by a factor of 3 with respect to that ofconventionally treated LSTO, along with a remarkable decrease of the activation energy. Thus, electric-field-assisted processes,usually known for their energy-saving character, can also be deemed as an attractive, forward-looking strategy for improvingfunctional properties of ceramics.