The thermo-mechanical simulator Gleeble 3800 was used in combination with the electron backscattered diffraction (EBSD) technique to analyze the austenite microstructure evolution during hot deformation in a low-carbon, microalloyed steel. The parent austenite grain structure was automatically reconstructed from EBSD datasets by applying the commercially available ARPGE software [Cayron, C., Artaud, B., and Briottet, L., “Reconstruction of Parent Grains from EBSD Data,” Mater. Charact., Vol. 57, Nos. 4–5, 2006, pp. 386–401]. The work aims at two aspects: the ability to quantify the austenite evolution depending on different process parameters, and the validation of the EBSD reconstruction software ARPGE to evaluate the accuracy of reconstruction and demonstrating the application in low-carbon steels. For these steels, the conventional metallographic methods like Bechet-Beaujard [Bechet, S. and Beaujard, L., “Nouveau réactif pour la mise en évidence micrographique du grain austénitique des aciers trempés ou trempés-revenus,” Rev. Met., 1955] are limited and not reproducible in determining the former austenite. The presented approach provides an attractive alternative. In this context, hot compression tests were performed on cylindrical samples using a Gleeble 3800 simulator to create defined austenite conditions. The samples were rapidly quenched after processing to preserve the austenite microstructure. The obtained bainitic/martensitic microstructure is an essential precondition for the reconstruction procedure. For the validation of the results, correlative measurements using classical metallographic techniques and ARPGE data were performed to check the reliability of the reconstruction. The results obtained in this study provide a direct correlation of the microstructure simulation by Gleeble and the austenite microstructure evolution during processing of low-carbon steels. Especially, austenite grain-growth phenomena and grain refinement could be successfully observed and quantified. Furthermore, the measurements show that even on large EBSD maps (1000 μm × 1000 μm), the shape of the austenite grains are calculated with good accuracy.