Multiple environment mechanical testing of solid-oxide fuel cells (SOFCs) and SOFC materials is critical to ensure appropriate compressive sealing in stack designs. Establishing the effects of temperature, environment, and porosity on the flexural strength of ceria-based SOFCs is a significant step toward practical deployment of the technology. This article presents research into these properties by use of a temperature and atmosphere controlled 3-point bend fixture capable of reaching Intermediate Temperature (IT)-SOFC operating conditions (650 degrees C). Gadolinium-doped ceria (GDC) samples with varying porosity and pore geometry were tested and it was determined that more spherical porosity contributed to improved flexural strength as compared with higher aspect ratio porosity. A linear strengthening effect was also observed with increasing temperature from ambient to 650 degrees C for GDC-based anode support layers and half-cell samples. Scanning electron microscopy was performed on fracture surfaces to identify fracture modes and to examine internal pore structures. Directionality of the applied stress with respect to the layered microstructure was found to have no measurable impact on mechanical properties in air, but orientation had a significant impact on strength of cells with reduced anodes. Additionally, with the support of thermogravimetric analysis, it was determined that after reduction, exposure to oxygen below 100 degrees C does not influence mechanical properties of the cells.