The electrical field used during heating within Spark Plasma Sintering (SPS) is considered to influence diffusion mostly through the development, movement and clustering of the vacancies. The consequences are modification of the local electronic structure and/or of the microstructure (e.g. of pore formation). These changes affect the functional properties of the material with or without additives. SPS also applies a uniaxial pressure on the sample producing bulks with a high level of density [1]. In the case of type II superconductors in a mixed state, dissipation of energy owing to vortex movement should be minimized. Therefore, for practical applications, pinning of the vortices is required for improved performance. Introduction of pinning centers through nanostructuring, use of additives, use of different technologies with specific features that can induce defects, irradiation and so on are of much interest. As mentioned in the previous paragraph SPS shows unconventional effects and they are expected to generate certain microstructures and defects suitable for effective vortex pinning. In this work we explore complex interdependencies between SPS processing, microstructure, defects and functional characteristics (such as critical temperature, critical current density, and irreversibility field) of MgB2 superconducting samples.