1 This is an Accepted Manuscript of an article published by Elsevier in Ceramics International, 47 (7), 9382 – 9391 on April 2021, available at: https://doi.org/10.1016/j.ceramint.2020.12.069 . It is deposited under the terms of the Creative Commons Attribution-NonCommercial- NoDerivatives License (http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited, and is not altered, transformed, or built upon in any way. Enhancing the electrical conductivity of in-situ reduced graphene oxide-zirconia composites through the control of the processing routine Cristina López-Pernía * a,b , Ana Morales-Rodríguez a , Ángela Gallardo-López a , Rosalía Poyato b a. Depto. de Física de la Materia Condensada. ICMS, CSIC-Universidad de Sevilla. Apdo. 1065. 41080 Sevilla. Spain b. Inst. Ciencia de Materiales de Sevilla, ICMS, CSIC-Universidad de Sevilla. Américo Vespucio 49. 41092 Sevilla. Spain Abstract Graphene oxide (GO) was mixed with 3 mol% yttria tetragonal zirconia polycrystal (3YTZP) using two powder processing routines: a colloidal method in an aqueous solution and a combination of ultrasonication with high-energy planetary ball milling in wet conditions. Highly densified 3YTZP composites with reduced GO (rGO) were consolidated by Spark Plasma Sintering. The in-situ reduction of GO was successfully achieved during the high-temperature sintering process and a detailed study of the * Corresponding autor. E-mail: cristinalopez@us.es (Cristina López-Pernía)