A process with fusion pre-treatment for synthesizing geopolymers and zeolites from fly ash, in particular X-type zeolites with pores of large dimensions and high capacity that utilize sea water and low incubation temperatures. Fly ash is initially mixed with NaOH to obtain a mixture, which is pulverized and then melted at the temperature of 550° C. After cooling, the melted mass is pulverized, dispersed in sea water with fixed ratios and left under stirring at ambient temperature for 12 hours. The incubation of the ground material in sea water takes place at a temperature of between 25 and 70 degrees centigrade. Once the incubation period is ended, the solid part is separated from the liquid phase (sea water) through centrifugation and subsequently rinsed and oven dried.