NOVELTY - Combustion of carbon-containing compound, comprises providing gas mixture comprising carbon monoxide or hydrocarbon and oxidant; and passing mixture through reaction chamber at gas hourly space velocity (GHSV) of at least 100000/hour and 400-1100degreesC. The chamber has an internal dimension of 1 cm or less. A combustion catalyst is disposed in the chamber.    USE - For combusting a carbon-containing compound.    ADVANTAGE - The method reduces emission of carbon monoxide and hydrocarbons into the atmosphere by converting them into carbon dioxide and water before being exhausted. It allows the combustion to occur at low enough temperatures such that formation of nitrogen oxide (NOx) is reduced. It is of low cost, provides high-energy efficiency due to low heat-transfer resistance, and has the ability to operate under a variety of conditions.    DETAILED DESCRIPTION - Combustion of carbon-containing compound, comprises providing gas mixture comprising carbon monoxide or hydrocarbon and oxidant; and passing mixture through reaction chamber at gas hourly space velocity (GHSV) of at least 100000/hour and 400-1100degreesC. The chamber has an internal dimension of 1 cm or less. A combustion catalyst is disposed in the chamber. At least 2% of carbon monoxide or hydrocarbon in the mixture is converted to carbon dioxide.    INDEPENDENT CLAIMS are also included for:    (1) a catalyst system comprising a metal substrate comprising chromium and cobalt; chromium-containing oxide layer in direct contact with the metal substrate, where the chromium-containing oxide layer has a surface that is not adjacent to the metal substrate and the surface has a cobalt:chromium ratio that is at least 50% less than the metal substrate; and active catalyst material on the chromium-containing oxide layer, where the combination of the metal substrate, active catalyst material and chromium-containing oxide layer defines a catalyst having a low surface area of not more than 0.5 m2/g or not more than 1 m2/inch2 of geometric surface area; and    (2) a method of making a catalyst comprising oxidizing a new metal substrate to form a metal with a layer of low surface area surface oxide, where the new metal substrate has not previously been part of a catalyst structure; sonicating the metal substrate with the low surface area surface oxide; and depositing an active catalyst material on the sonicated metal substrate with the low surface area oxide layer.