Efforts to fulfill the needs of electricity in Indonesia are still dominated by the use of fossil fuels such as coal in Steam Power Plants. However, the process of burning coal causes various environmental problems, one of which is fly ash. Fly ash is classified as a dangerous and toxic material. Although it is regarded as hazardous material, fly ash contains silica (SiO2) and alumina (Al2O3) which can be used as raw material for synthesis of aluminosilicate-based materials such as geopolymers, zeolites and others. In this study, the chemical composition, SiO2/Al2O3 ratio, and fly ash type will be examined from three different sources of fly ash such as power plants owned by a private company located in the Kapuas area (FA1), Asam-Asam's (FA2), and PulangPisau's (FA3) power plant. The chemical composition was tested by ASTM D 3682-13. Based on data, FA1 has the highest SiO2 and Al2O3 composition with a percentage of 56.44% and 31.31%, respectively. FA2 has the highest Fe2O3 composition with a percentage of 23.10% and FA3 has the highest CaO composition with a percentage of 23.46%. The highest SiO2/Al2O3 ratio is 4.61 from FA2, while the lowest SiO2/Al2O3 ratio is 1.80 from FA1. Based on the chemical composition of fly ash, FA1 and FA2 are classified as F type, while FA3 is classified as C type. From these data, it can be concluded that the fly ash from the three power plants still have the potential to be used as source for synthesis of aluminosilicate-based materials.