ABSTRACTIndian coal fly ash generally comprises 50–60% SiO2SiO2$Si{O}_2$, and 25–35% Al2O3Al2O3$A{l}_2{O}_3$ can potentially replace bauxite as an aluminum resource. Aluminum recovery from coal fly ash is highly dependent on removing amorphous silica, activating the inactive mullite phase, and increasing the Al/SiAl/Si$Al/Si$ ratio. This work thoroughly investigated and compared the alkali-desilication operation by two widely used alkalis, KOHKOH$KOH$ and NaOHNaOH$NaOH$, based on four operational parameters: liquid-to-solid ratio, KOHKOH$KOH$ or NaOHNaOH$NaOH$ concentration, leaching time and temperature. Using SEM, EDX, and XRD, the morphology and phase of fly ash and solid byproducts were analyzed. NaOHNaOH$NaOH$ was more effective than KOHKOH$KOH$ in SiO2SiO2$Si{O}_2$ dissolution at all operational parameters. A 20 wt% concentration, 5:1 liquid-to-solid ratio, 2hrs leaching time, and 100°C temperature were the optimum removal conditions for silica from fly ash using NaOHNaOH$NaOH$. With KOHKOH$KOH$, the ideal desilication conditions were obtained at 28 wt% concentration, 3hrs leaching time, and 150°C temperature. The highest Al/SiAl/Si$Al/Si$ ratios were obtained under the same optimal desilication conditions. Using KOHKOH$KOH$ and NaOHNaOH$NaOH$, the Al/SiAl/Si$Al/Si$ ratio was enhanced from 0.58 to 1.26 and 1.45, respectively. The main zeolitic products obtained were Hydroxysodalite in NaOHNaOH$NaOH$-treated fly ash and Linde F zeolite and Kalsilite in KOHKOH$KOH$-treated fly ash.