This work presents the results of synthesis of zeolites from perlite and fly ash microspheres via treatment with sodium hydroxide solution, at low temperatures of 30-90 degrees C under atmospheric pressure. Obtained products could be active as low-cost agents for the removal of heavy metals from wastewater. The influences of reaction temperature and time as well as NaOH concentration, on the type of the solid products were investigated. The results showed that mixture of zeolite Y, A and Na-P-1 could-be synthesized at temperatures varying in the range of 60-90 degrees C with NaOH concentration of 3-4 M. Regardless of the type of substrate used, it is possible to obtain the product in a similar way. The synthesized products are characterized by low bulk density, 0.16 and 0.95 g/cm(3) for perlite and microspheres respectively. (C) 2013 Elsevier Ltd. All rights reserved.