We have demonstrated the use of STXM spectromicroscopy to probe the nanoscale morphology and chemistry of hematite nanorods used as photoanodes in solar water splitting process. Two analytic approaches are presented, derived from reference spectra recorded from commercial hematite and synthesized hexahydrate iron chloride. The elemental continuum of the X-ray absorption spectra (away from the O K-and Fe L2,3 edges) cannot be reproduced simply from the scattering factors given in the Henke tables using the expected elemental composition. To achieve a good fit, we needed to use a linear combination of the experimental spectra measured from hematite and hexahydrate iron chloride. Choosing different ROIs and extracting the iron phase ratio evidenced heterogeneous chemistry along the nanorod, but with poor quantification. SVD, used as a second analytic approach, gave much more consistent and convincing results. First, to our astonishment, the chemical component map for hematite from the SVD analysis revealed with very good resolution that the hematite single nanocrystal was spatially separated in the interior of the nanorod. Second, thickness quantification mapping revealed the spatial distribution of the two iron phases, showing that the akaganeite to hematite phase transformation occurs from the tips of the nanorods. Finally, the particular morphology of the nanorods, i.e. exposing mostly hexahydrate iron chloride to the electrolyte, explains, through its acidic character, why the onset potential values estimated for these photoanodes were significantly lower than for the epitaxial hematite photoanodes.