A range of metal silicide interference filters has been prepared on various metal substrates and aged in vacuum at elevated temperatures. These show promise as high‐temperature stable selective surfaces for solar energy phototheral conversion. Solar absorptances 75%–80% and emittances of about 2% can be obtained at room temperature for homogeneous metal silicide films on bulk copper. Higher absorptances are obtained using sputteredcopper, bulk stainless steel, or evaporated nickel substrates. Emittances of homogeneous metal silicide films on bulk copper increase to about 5% at 500°C. The solar absorptance of an iron silicide on copper surface was temperature independent up to 500°C. Absorptances greater than 90% can be obtained for multilayermetal silicide films on copper. The emittances of these films are somewhat higher than for homogeneous films.