Large quantity of fly ash is generated every year from the electric power plants. Due to the shortage of disposal sites and tighter regulations, new viable ways of utilizing fly ash are needed. The formation of a porous material comprising fly ash was investigated. It was found that a porous material can be made by mixing fly ash with phosphoric acid, followed by heat treatment. The porous material is light-weight (bulk density ˜1 g/cm3), machinable, and with reasonable strength. Due to the high percentage of close porosity, the porous material has a great potential for thermal insulation applications.