China produces roughly half of the world's cement, a large share of which is made in energy inefficient, highly polluting kilns. The cement industry is a major source of multiple air pollutants, among them dioxins, mercury, particulate matter and greenhouse gas emissions. In 2005, just over one billion tons of cement was produced in China and cement demand will continue to be high in the near future as development goals are pursued. In the kiln, production of clinker, the main ingredient of cement, consumes about 80% of the energy used at a cement plant. Clinkering is also the source of almost all carbon dioxide and toxic emissions produced from cement manufacture. This paper examines measures that can be used to retrofit or to replace older, inefficient Chinese cement kilns to improve their energy efficiency, reduce pollution and maximize the industry's economic performance and output. We provide costs, savings and payback periods upon implementation for case studies around the world, and where possible, specifically in China. Fourteen of the technologies and measures examined have simple payback periods of three years or less.