Fluorescent lamps are widely used world-wide due to their long life and energy saving capability. These lamps contain mercury (Hg) as a source of fluorescent radiation. The object of this study is a new technology for physicochemical treatment of waste fluorescent lamps. The residuals of the technological process were evaluated for potential leaching of heavy metals into the environment. Evaluation was performed using standardized extraction tests. Additionally, X-ray diffractometry (XRD) analysis, as well as tests with complex-forming agents and under pH-stable conditions were performed aiming to predict stability of the residuals in various environmental conditions. According to the XRD analysis, the minerals fluorapatite and hydroxylapatite were dominant in analyzed samples. The results of total extraction by aqua regia revealed that residuals contain relatively high total concentrations of Hg, Mn, and Zn. Concentrations of heavy metals, leaching to aqueous solution, were compared to leaching limit values (according to EU legislation). The concentrations of available Hg in the waste fluorescent lamp treatment products, according to its solubility in the water, exceed the limit values. The measured water-leachable Hg concentration was 4.88 mg kg(-1), while the value for waste acceptable at hazardous waste landfill sites is 2 mg kg(-1). Concentrations of other measured heavy metals did not exceed the limit values. According to the results, Hg stabilization potential for presented technology exceeds 99%.