Gas-generating solid compositions usually include a compound that decomposes at high temperatures and an energetic additive that provides heat for self-sustained combustion. The present paper investigates the feasibility of using nanocomposite reactive materials produced by arrested reactive milling as energetic additives in oxygen and hydrogen generators. In such reactive materials, components are mixed at the scale of about 100 nm, but are not chemically bound. Thermodynamic calculations of the adiabatic flame temperature and combustion products have been conducted for the mixtures of sodium chlorate and ammonia borane with various reactive compositions. Analysis of the obtained results indicates which additives are the most promising. Experiments with sodium chlorate/iron mixtures, ignited with a hot wire technique, have shown a reasonable agreement with thermodynamic calculations. An experimental facility for laser ignition of gas-generating compositions has been constructed. The facility involves infrared video recording and mass-spectrometry.