Mesostructured cellular foam (MCF) silica is commonly prepared from tetraethyl orthosilicate, which is an imported chemical in Indonesia. To substitute this chemical, palm oil boiler ash (POBA), a locally sourced and environmentally friendly material, was used as replacement. Based-on this alternative, acetic acid and potassium chloride were utilized rather than hydrochloric acid solution and mesitylene, so that a green synthetic process could be developed. The experiments involved conversion of POBA to MCF silica through an extraction process with dilute sulfuric acid solution, formation of sodium silicate using sodium hydroxide, and synthesis of MCF silica from sodium silicate, where the process factors were varied during the experiments. The SiO2 content in POBA was low, but it increased to 52.838% (w/w) after the extraction. The content of more than 75% (w/w) was obtained after treatment with NaOH. The optimum MCF silica had specific surface area of 738.976 m²/g, specific pore volume of 2.046 cm³/g, pore cell diameter of 167.114 Å, and pore window diameter of 97.757 Å. The product was developed by 40 mL of 3M sodium hydroxide, 5 grams of Pluronic® P123, 4.4 mL of acetic acid, and 5 grams of potassium chloride. Effects of the operational factors were observed during synthesis. Immobilization efficiency of glucoamylase enzyme was found as high as 73.33% resulted at temperature of 35°C, Sorensen phosphate buffer pH of 6.0, initial free enzyme concentration of 8% (w/v), and stirring speed of 120 rpm. Hydrolytic capability of immobilized glucoamylase was observed at different temperature to give the maximum dextrose equivalent (DE) value of 56.61% (w/w) (tapioca substrate) and 15.37% (w/w) (sorghum substrate), at the optimum temperature of 70°C. These results were lower compared to free glucoamylase DE value, which produced DE value of > 80% (w/w).