Chromium may act either as a catalyst or an inhibitor of different animal and vegetable metabolic processes depending on its oxidation state. Anionic compounds of Cr(VI) (CrO₄^2-, Cr₂O₇^2-), are dangerous environmental pollutants due to their high solubility wereas Cr(III) shows a lower toxicity in biological systems. As both the mobility and toxicity of chromium are strictly related to its oxidation state, redox and complexing reactions play a great role in determining its fate in the environment. In this review we report about some factors which regulate the dynamics of chromium, in oxidized and reduced forms, in the soil-root system. Particular attention was paid on the role of synthetic humic acids (RHA) and important biomolecules such as uronic and phenolic acids on the chromium detoxification processes.