The exhaust valve in the internal combustion engine was the first engineering component requiring strength and oxidation resistance at temperature. It was critical to the improvement of power units for motor cars and aircraft. The best valve alloy, up to 1915, was a tungsten tool steel, itself a serendipitous development. It had good strength, but poor resistance to oxidation. Fortunately, rust resistant stainless steels, and wear resistant cobalt alloys, containing chromium, were coming into production, and were found to have good oxidation capability. But the first group of alloys with really good oxidation properties were nickel-chromium alloys, specifically developed for resistance wires in bread toasters. These three groups provided the basis for all future developments in exhaust valve metallurgy. By 1930, an engineering science approach to alloy design was emerging, but progress was largely empirical, with a requirement to deeper understanding only emerging with the invention of the jet engine.