Hydrogen production is a crucial process for the worldwide green energy transition on the way to independence from fossil fuels. High temperature solid cells (SOCs) play an important role in this process as they can produce green hydrogen with a high efficiency at T=850 °C (solid oxide electrolyser cells, SOECs) and can also work in reverse (solid oxide fuel cells, SOFCs). For the cost-optimization of electrolyte-supported SOCs, an important property is the mechanical stability of the cell, which is mainly provided by the cell electrolyte. In this study, the authors investigated properties of 3YSZ ceramic foils (t < 90 µm) for SOCs applications, which allows the evaluation of a large material volume compared to the more common ring-on-ring or ball-on-three-ball test. To realize the test, dogbone-shaped samples are coupled with a hook-shaped gripping system using metallic cap stripes for the transmission of load and a swivel head for the misalignment minimization. To evaluate the influence of edge quality on the strength, the samples were cut with a laser and subsequently ground with three grinding tools with different diamond grain sizes. All ground samples were found to have an average strength above 1000 MPa, while the lasered ones show strengths below 500 MPa. The sample edges were analysed via SEM to investigate the influence of roughness on strength. For a coarser diamond grain size on the grinding tool the standard deviation was higher, but the strength did not vary compared to the one ground with a finer diamond grain size. Moreover, XRD measurements were performed on the sample edges to evaluate the phase transformation (tetragonal to monoclinic 3YSZ) during grinding.