The experiment aims want to compare the combustion pyrometamorphism of limestone, which represents the natural analogous of cement production, and cement materials, by means of ex-situ and in-situ high-temperature Synchrotron X-Ray Powder Diffraction. Combustion pyrometamorphism is a poorly understood geological process involving sedimentary rocks in a first stage of high-temperature combustion , followed by a late hydration stage, leading the formation of natural analogous of anhydrous and hydrated cement, respectively. The main focus of the experiment is to get accurate data on (i) mineral assemblages, (ii) crystallographic parameters (cell parameters, coherent domain size and microstrain), (iii) chemical reactions and (iv) phase transitions during heating of limestone. The results will be useful for geology, leading a deeper understanding on combustion pyrometamorphism, and cement manufacture, trying to discover new cement type for reducing the environmental impact.