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Technologies for mass production require cheap and abundant materials such as ferrous chloride (FeCl₂). The literature survey shows the lack of experimental studies to validate theoretical conclusions related to the population of ionic Fe-species in the aqueous FeCl₂ solution. Here, we present an in situ X-ray absorption study of the structure of the ionic species in the FeCl₂ aqueous solution at different concentrations (1–4 molL⁻¹) and temperatures (25–80 °C). We found that at low temperature and low FeCl₂ concentration, the octahedral first coordination sphere around Fe is occupied by one Cl ion at a distance of 2.33 (±0.02) Å and five water molecules at a distance of 2.095 (±0.005) Å. The structure of the ionic complex gradually changes with an increase in temperature and/or concentration. The apical water molecule is substituted by a chlorine ion to yield a neutral Fe[Cl₂(H₂O)₄]⁰. The observed substitutional mechanism is facilitated by the presence of the intramolecular hydrogen bonds as well as entropic reasons. The transition from the single charged Fe[Cl(H₂O)₅]⁺ to the neutral Fe[Cl₂(H₂O)₄]⁰ causes a significant drop in the solution conductivity, which well correlates with the existing conductivity models.