This study investigates the role of metastable oxygen species on a nickel (Ni) catalyst during the dry reforming of methane (DRM). Using environmental scanning electron microscopy (ESEM), near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), online product detection, and computer vision, the researchers found that different forms of oxygen—atomic surface oxygen, subsurface oxygen, and bulk NiOy—coexist on the catalyst and exhibit distinct catalytic activities. The sequential transformation of these metastable oxygen species leads to rate oscillations in DRM. The imaging approach allowed the localization of fluctuating surface regions that correlated directly with catalytic activity. The study highlights the importance of metastability and operando analytics in catalysis science, providing insights for the design of more efficient catalytic systems. The findings suggest that the metastability of oxygen species on the Ni catalyst is a key factor in the oscillatory behavior observed during DRM, with the different forms of oxygen having distinct levels of activity and transforming into each other through various chemical reactions. This work contributes to a deeper understanding of the complex dynamics of heterogeneous catalysis and offers potential strategies for stabilizing the active state of catalysts.This study investigates the role of metastable oxygen species on a nickel (Ni) catalyst during the dry reforming of methane (DRM). Using environmental scanning electron microscopy (ESEM), near ambient pressure X-ray photoelectron spectroscopy (NAP-XPS), online product detection, and computer vision, the researchers found that different forms of oxygen—atomic surface oxygen, subsurface oxygen, and bulk NiOy—coexist on the catalyst and exhibit distinct catalytic activities. The sequential transformation of these metastable oxygen species leads to rate oscillations in DRM. The imaging approach allowed the localization of fluctuating surface regions that correlated directly with catalytic activity. The study highlights the importance of metastability and operando analytics in catalysis science, providing insights for the design of more efficient catalytic systems. The findings suggest that the metastability of oxygen species on the Ni catalyst is a key factor in the oscillatory behavior observed during DRM, with the different forms of oxygen having distinct levels of activity and transforming into each other through various chemical reactions. This work contributes to a deeper understanding of the complex dynamics of heterogeneous catalysis and offers potential strategies for stabilizing the active state of catalysts.