Abstract Monolithic gels in the Na 2OP 2O 5SiO 2 system were prepared by a sol-gel technique. Ionic conductivity, differential thermal analysis (DTA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and powder X-ray diffraction (PXD) data are reported. Comparison of structural and thermal properties of the Na and Li gels in this system show that they are similar; however, the crystallization behavior of the Na and Li systems differ. Li, Na and K gel analogs of identical composition were prepared in the A 2OP 2O 5SiO 2 system. The ionic conductivity of the gels was found to increase with increasing ionic radii of the alkali metal ions σ K ≥ σ Na ≥ σ Li.