The dataset contains the numerical data used to produce figures 2-14 and S1-S8 (Figure 1 is purely schematic and is uploaded as a tif file for completeness - it does not contain any new data). These files contain the transient UV-visible, X-ray absorption, and X-ray emission data that were used to characterize the dynamics of methyl cobalamin at neutral pH and to compare this to adenosyl cobalamin. Details of data collection and reduction are provided in the associated manuscript. Data files are all text files which contain tab-delimited columns of data corresponding to each figure in the manuscript.