A plate reactor was designed to investigate the catalytic soot oxidation applying glass ceramic plates coated with lithium zirconate. The results are compared to the corresponding powder catalysts in thermogravimetric experiments. The deposition of soot by spray coating resulted in an intimate contact mode equivalent to the mortaring preparation of the tight contact powder samples. In the presence of lithium ions the soot oxidation temperature was decreased significantly both in the thermobalance and in the plate reactor.