Abstract The nanoporous alumino-borosilicate (Al-B-MCM-41) has been developed for the removal of Cesium (Cs) from liquid wastes and further processed for its stable immobilization. The prepared novel sorbent was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray di_raction (XRD), nitrogen porosimetry, scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), and transmission electron microscopy (TEM) techniques. The e_ect of different experimental parameters such as initial pH solution, contact times,temperature, and initial Cs concentration on the sorption capacity of the nanoporous Al-B-MCM-41 was evaluated. According to the obtained results, Al-B-MCM-41 o_ered the maximum Cs sorption capacity of 119.05imgigf1. For stable immobilization of the sorbed Cs ions, the Cs-containing nanoporous Al-B-MCM41 were subjected to heat treatments at various temperatures. To investigate the leaching of Cs from heat treated samples, the leach tests were performed using di_erent eluents. Results showed that treating sample at about 1100i°C leads to an e_ective stabilization of Cs in the Al-B-MCM-41 matrix since only 1.9% of the initially sorbed Cs was leached out. Finally, sorption of Cs-137 from real radioactive waste and its stabilization at the optimal temperature was evaluated.