Here, glass in the composition of 25K 2 O-25Nb 2 O 5 -50SiO 2 (mol%) doped with Nd 2 O 3 (0.5 wt.% in excess) was isothermally crystallized at 800 °C for 1-100 h. Their structures, dielectric and optical properties were analyzed with the progress of nanocrystallization of Nd 3+ : KNbO 3 by XRD, FESEM, TEM, FTIRRS, DC, optical absorption and fluorescence measurements. Crystallization of KNbO 3 is confirmed from XRD and the appearance of 749 cm À1 band in the FTIRRS spectra. The crystallite size estimated from XRD and TEM is found to vary in the range 7-11 nm. The formation of ferroelectric nano-crystalline KNbO 3 phase is also attributed by a steep rise in the dielectric constant (e) of glass-ceramics with heat-treatment time. The measured photoluminescence spectra have exhibited emission transitions of 4 F 3/2 ? 4 I J (J = 9/2, 11/2 and 13/2) from Nd 3+ ions upon excitation at 817 nm. It is observed that the photoluminescent intensity and excited state lifetime of Nd 3+ ions initially decrease and then gradually increase with increase in heat-treatment time. The absorption spectra and fluorescence measurements disclose that the Nd 3+ ions gradually enter into the KNbO 3 nanocrystals.