Most metals used in manufacturing require surface treatment for essential functionalities, including: corrosion resistance, paint adhesion, surface appearance, and/or tactile finishing. Chemical conversion coating is one of the surface treatment methods that provides anti-corrosion properties, and widely used in automobile and other industries. Here we investigated an environmentally friendly chemical conversion method, Zr-based, dilute hexafluorozirconic acid (H₂ZrF₆) treatment. This method attracted attention because it is phosphate-free and easy to apply, however without clear reaction mechanism. This study focuses on the elemental distribution of the coatings, the change of element concentration and species during the immersion treatment using in situ synchrotron X-ray fluorescence microscopy (XRF) and X-ray Absorption Spectroscopy (XAS). Also, we treated the sample in the solution at certain temperature and time range. Scanning electron microscopy (SEM) and focus ion beam (FIB)-SEM were also used to see the surface and cross-section morphology change before and after the surface treatment. Then by comparing the coating thickness, surface cluster density and cluster size to seek the kinetics of coating formation process. As such, we could determine the mechanism of the coating formation via surface chemical conversion.