studied the kinetics over 11.7 ~ 177.5 K, and found almost two orders of magnitude increase in the rate coefficient from 175 to 100 K. Gómez Martín studied the kinetics of the title reaction over 56 ~ 202 K, and confirmed that at temperatures below 180 K, the R2 channel dominates due to the quantum tunneling. Theory is very helpful to provide the dynamic detail along the reaction. The potential feature largely determines the reaction kinetics and dynamics. As shown in Figure , both R1 and R2 channels have apparent barriers, TS1 and TS2, sharing the same pre-reaction complex, RC, which has been characterized also experimentally. There exist two different product complexes, PC1 and PC2, before arriving at the final products, H2O + CH2OH and H2O + CH3O. The former product channel is ~10 kcal/mol more exothermic than the latter, and the energy difference between PC1 and PC2 is also similar, ~ 11 kcal/mol. TS1 is ~ 2 kcal/mol lower than TS2. Indeed, the reaction mechanisms of R1 and R2 channels for the title reaction have been studied by various electronic structure levels of theory, such as MP2, MP4, DFT, QCISD(T), G2, CCSD(T), CCSD(T)-F12a and CASPT2, and the kinetics were then determined by statistical rate theories, like transition state theory (TST), Rice-Ramsperger-Kassel-Marcus (RRKM), or master equation. As shown in Figure , theoretical results are generally consistent with experiment at temperatures above ~300 K. At interstellar low temperatures, kinetics computations based on high-level ab initio information also predicted that the rate coefficients were increased, consistent with experiment, due to quantum tunneling effect. However, the experimental results are still significantly higher than the kinetics calculations. The theoretical studies by Siebrand et al. suggested that methanol dimers can play a significant role in the interstellar low temperature kinetics, which was questioned by the combined experimental and theoretical investigation. Except the statistical rate theories, dynamic methods, including quasi-classical trajectory (QCT), ring-polymer molecular dynamics, and quantum dynamics (QD), can provide rate coefficients and dynamic details. Roncero et al. developed a full dimensional potential energy surface (denoted as PES-2018) for the reaction OH + CH3OH, and carried out QCT calculations under 100 K. The results showed the reactivity was increased at low temperature / energy due to the complex forming mechanism.