Tuning the coordination environment is the research axis of single atom catalysts (SACs). SACs are commonly stabilized by various defects from support. Here, we report a lattice confined Pd SAC using MnO2 as support. Compared with the Pd clusters anchored on the surface, the lattice confined Pd single atoms allows spontaneous exaction of surrounding lattice oxygen at room temperature when employed in CO oxidation. The MnO2 supported Pd SAC exhibited a high turnover frequency of 0.203 s(-1) at low reaction temperature, which is higher than that of recently reported Pd SACs. Theoretical calculations also confirmed the confined monatomic Pd activate lattice oxygen with an ultralow energy barrier. Our results illustrate that the unique coordination environment of single atom provided by lattice confinement is promising to boost the activity of SACs. (C) 2021 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by ELSEVIER B.V. and Science Press. All rights reserved.