The paper presents the investigation on the estimated efficiency of iron (III) chloride solutions in the decontamination process of radioactive soils with ⁹⁰Sr, according to kinetic and thermodynamic characteristics of the desorption process. The specific ⁹⁰Sr radioactivity of soil samples was (3.9±0.3)·104 Bq·g. The adsorption isotherms of Sr²⁺ and Fe³⁺ are described with the Langmuir equation. The values of Gibbs energy G0298 = -4.65 kJ·mol^-1 and equilibrium ion exchange constant Keq = 6,5 confirm the hypothesis of strontium removal from soils with iron (III) cations. The effectiveness of the method is substantiated by experimental and calculated results of this study samples of radioactive soils are deactivated in 90% after 9.5 hours, whereas the kinetic constant is 6.77·10 s^-1. The suggested method of soil cleanup with 0.2 M Fe³⁺ solutions is optimal and complies with the environmental requirements.