Thermal stability of deposited Si-B-C-N materials (film fragments or powders without a substrate) in inert gases (He and Ar) up to 1700 degrees C was investigated using differential scanning calorimetry, high-resolution thermogravimetry and X-ray diffraction measurements. Amorphous Si-B-C-N films were fabricated by dc magnetron co-sputtering of a single B(4)C-Si target in two nitrogen-argon gas mixtures (50% N(2) + 50% Ar or 25% N(2) + 75% Ar). It was found that the deposited Si-B-C-N materials can be more stable at high temperatures in the inert atmosphere than the usually used substrates (e.g. SIC or BN). The materials with the compositions (in at.%) Si(32-33)B(10)C(2)N(50-51), for which N/(Si + B+ C) = 1.1-1.2, retained their amorphous structure up to 1600 degrees C without any structural transformations and detectable mass changes. (C) 2010 Elsevier B.V. All rights reserved.