For the decontamination of radioactive Cs-134 and Cs-137 using magnetic collection, a new composite material consisting of a Na-P1-type zeolite and magnetite was synthesized from the waste fly-ash from thermal power stations and iron chlorides. The presence of nanosized magnetites in the polycrystalline zeolite (several micrometers) was confirmed by TEM observations. The cation-exchange capacity (CEC) and magnetic properties of these composite materials were characterized.