Mercury not only is one of the most toxic inorganic pollutants that threaten the environment and living organisms but also presents a number of challenging analytical problems due do its peculiar chemical properties and behavior. In this study, we have been investigating the distribution and speciation of Hg in the solid phase of soil samples collected in an industrial site in the South of Italy polluted by chlor/alkali plant emissions by using different analytical techniques. Both conventional and more advanced analytical methods are being adopted. The total amount of mercury in these soils ranged from 1 to 50 μg/g as determined by direct analysis on solid soil samples performed by an automated Hg-analyzer. At a first instance, Hg distribution in operationally-defined soil fractions was assessed by a specific sequential extraction procedure as well as by Hg thermal-desorption analyses. From these investigations Hg was found speciated in scarcely soluble forms, most probably as Hg(0) (90%) and HgS (10%). These data were supported by SEM-EDX observations that evidenced the presence of Hg mostly in soil particles smaller than 2 μm. According to these findings, the amount of Hg that was quantified in the clay fraction (<2 μm) was from 2 to 10 times higher than in the overall soil samples sieved at 2 mm. The mineralogical composition of the fraction <2 μm was also carefully determined by XRD. Detailed Hg distribution in the soil colloidal fraction is being studied by using Sd-FFF-ETAAS (Sedimentation Flow Field Fractionation coupled to Electro-Thermal Atomic Absorption Spectroscopy) to identify the most relevant Hg-bearing fractions. In addition, XANES and EXAFS measurements on different solid soil fractions are providing more direct and detailed information on Hg speciation. The first observations using synchrotron radiation (combined μ-XRF and μ-XRD) on soil thin sections revealed the presence of microscopic cinnabar (HgS) particles.