Vitreous materials when subjected to thermal treatments at high pressure present different structures from those obtained at atmospheric pressure. The objective of this work is to investigate the changes in the structure and properties of the barium disilicate glass-ceramic when subjected to thermal treatment to promote the nucleation and crystal growth at pressures up to 7.7 GPa. In this work the Barium disilicate glass (BaO•2SiO₂) was produced at atmospheric pressure following the conventional route of melting quenching. The glass formed was submitted to the differential thermal analysis (DTA) for identify the glass transition temperature (Tg) and crystallization temperature (Tc). The results indicate Tg in 690ºC and Tc1 in 860ºC and Tc2 in 960°C. The sample was subjected to thermal treatment at 710°C in the time range of 120-300min for the nucleation process following the thermal treatment for crystal growth at 860°C for 30-120min (atmospheric pressure). The second group of samples was submitted to high pressure for investigate the densification and phase transition. The experimental results were obtained using a toroidal type high-pressure chamber up to 7.7 GPa in controlled temperature (room temperature to 860°C). The characterization of the samples was performed using X - ray diffraction, Raman spectroscopy, optical microscopy and hardness measurements using the Vickers indentation test. The results indicate that there is a shift of Tg and Tc to low temperatures for samples submitted previously to high pressure and room temperature in comparison of samples not densified. The crystallization samples in high pressure and high temperature show that structure is distinct than formed in atmospheric pressure for same temperature condition. The hardness investigations are being with Vickers indentation method, for investigate the hardness and cracks in the all samples. The amorphous glass, glass-ceramic produced in distinct experimental condition was analyzed and preliminary results indicate that mechanical properties are changed whit application of high pressure.