K–Ca–Si–O glass was applied to metal supports for use as a catalyst for diesel soot combustion. Glasses were processed from the melt and by a sol–gel route. Catalyst activity for the oxidation of diesel exhaust soot and flame soot from an oil lamp was compared by thermogravimetric analysis (TGA). The results show that a K-based catalytic glass coating on metal substrates can reduce the temperature where half of the engine soot is oxidized (T 50 ) to as low as 360°C under loose contact conditions, and offers catalytic stability for long term combustion cycling. Scanning electron microscopy observations show that sol–gel glass processing is effective for coating complex wire mesh shapes without pore clogging.