Silicon nanoparticles which have an average size of 1 nm are synthesized using electrochemical methods and their stability under high temperature and humidity conditions have been investigated. These types of Silicon nanoparticles exhibit strong blue emission (centered around 420 nm) upon excitation with ultraviolet illumination. Standard heating procedures showed that, these nanoparticles in a liquid suspension (de-ionized water) are stable to heating and they retain characteristic emissions even at elevated temperatures. Thin solid films of such Silicon nanocrystals also show good stability under plasma and oxidizing environments at high temperatures.