Sorption behavior of Cs+ and Ba2+ ions on Magnesite was studied using the radiotracer method complemented by x-ray photoelectron spectroscopy (XPS). 137Cs and 133Ba were used as radiotracers. The batch method was used. Local tapwater containing primarily Na+, K+, Ca2+ and Mg2+ ions was used as the aqueous medium. For kinetic studies samples were shaken for periods ranging from one hour to seven days. Aliquots of the aqueous phase before and after shaking were counted using a 35 cm3 pure Ge detector. Magnesite samples were separated into various size fractions by dry and wet sieving. Both fractionated samples and unfractionated samples (particle size < 107mµ) were used. In the XPS the spectra were recorded using a KRATOS ES-300 spectrometer with Al Kα source. Sorption isotherm studies were carried out at 30, 40, 50, 60 and 70 °C.