criteria can narrow the candidate space from thousands of oxides to just a handful. At each down-selection criteria we have highlighted one material among many that appear interesting due to relatively low prediction uncertainty, relatively wide stability range, high cation/structure complexity, verified experimental synthesis, and a lack of any STCH-specific experimental investigations that we are aware of. Importantly, this screening "rediscovers" the known STCH material BCM-12R. However, it is eliminated by stricter down-selection criteria since the "Element-only" encoding model under-predicts the oxygen vacancy enthalpies with {2.0 ± 0.3, 2.9 ± 0.4} eV for the two O sites in BCM, compared to the "Full" encoding predictions, {2.6 ± 0.3, 3.8 ± 0.5} eV, and DFT predictions, {2.66, 3.29} eV (Figure ). This emphasizes the prudence of considering materials inclusive of their uncertainty, especially since the "Element-only" model necessitated by MP screening has slightly higher CV error. Some oxides with a relatively simple composition satisfying strict down-selection criteria include: Mn 3 O 4 , Fe 3 O 4 , Fe 2 O 3 , Ba 2 Fe 2 O 5 , Mn 2 CoO 4 , Mn(FeO 2 ) 2 , Sr 2 Mn 2 O 5 , Sr 3 (FeO 3 ) 2 , Ba(FeO 2 ) 2 , Ba 3 In 2 O 6 , Fe 2 NiO 4 , and Sr 5 Mn 5 O 13 , All have been experimentally synthesized in the literature. Notably, several have already been investigated in the context STCH performance or other water splitting approaches. Rediscovering these known STCH materials further validates our approach, and we have now identified many new candidates from which promising STCH materials can be experimentally targeted (see Table for details and the comprehensive list). Raw data for all predicted defect properties and customizeable open source scripts for reproducing or modifying the down-selection criteria can be found in the project's Zenodo repository. 49