The aim of this research is to synthesize mesoporous silica directly from the bottom ash waste through the melting method using alkali at high temperatures. The resulting mesoporous silica will be used as CH4 gas adsorbent. The bottom ash waste was firstly separated by Fe and Ca using 37% HCl followed by melting at high temperatures and producing silica extract. The extract will be used as the basic material for making mesoporous silica which impregnation with PEG 4000. The resulting solids will then be characterized using XRD and BET. The result of mesoporous silica was then carried out by measuring CH4 gas adsorption capacity by gravimetric method with interval temperature of 30, 40, and 50 °C and pressure of 1, 3, and 5 atm.