Increasing demand for energy has led to an increase in the utilization of coal and, subsequently, in producing large quantities of fly ash as a waste product. Since fly ash is enriched with SiO2 and Al2O3, this waste product can be transformed into zeolite-like crystalline materials as a result of chemical treatment. In this study, the change in the porous structure of Pha Lai thermal-power plant fly ash chemically treated with HCl and NaOH 2 M solutions at 50°C was examined. The results showed that the NaOH-treated fly ash (FA-NaOH) had a much greater specific area (SSA) and pore volume than the HCl-treated fly ash (FA-HCl) and untreated fly ash (FA). The XRD patterns showed the presence of NaP in the FA-NaOH. The FE-SEM images showed that after the NaOH treatment, FA changes its shape of smooth balls into the rough surfaces, but not in the case of FA-HCI. The obtained results predict that FA-NaOH could be used as the efficient adsorbent for environmental pollutant removal.