This paper evaluates the toxicity associated with two industrial wastes used as raw material of geopolymers. These wastes are fly ash (FA) and spent catalyst catalytic cracking (FCC). The residues were characterized using techniques such as XRF, XRD, SEM and laser granulometry. Two geopolymers systems based on FA-100% and FCC-100% were produced using SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> molar ratios of 6,0 and 2,4 and Na<sub>2</sub>O/SiO<sub>2</sub> of 0,20 and 0,25 respectively. The technique TCLP (Toxicity Characteristic Leaching Procedure) was applied in order to evaluate the toxicity. Cr, V, Zn, Ni, As, Ba, Sr, Pb and Cd elements were analyzed. The results indicate that concentrations of heavy metals leachate (except V and As) are low compared with the environmental standards. The geopolymers studied are considered effective in terms of inmobilizing contaminants.