The production of cement releases large quantities of carbon dioxide and is the third-largest anthropogenic source after fossil fuel combustion and land-use change. Global estimates of these emissions have varied considerably. Here we present a new database of country-level process emissions of CO₂ from the production of cement, combining the best available sources. The global data series covers the period 1928–2016. Emissions in 2016 were 1.45 ± 0.20 Gt CO₂.