The corrosion products formed during the anodic polarization of molybdenum in 1 M KOH were investigated in situ with time-resolved X-ray absorption spectroscopy at the Mo K-edge. Near edge spectra (XANES) as well as EXAFS scans extending over approximately 1000 eV above the Mo absorption edge were measured as a function of the corrosion time. Time dependent values for the concentration of the dissolved Mo species in the electrolyte were calculated from the change of the absorption cofficient at the absorption edge. The detailed analysis of the XANES and EXAFS data suggests the presence of MoO42- ions in the solution.