Reliable national statistics are fundamental for climate change science as well as for global negotiations about future emission targets and the allocation of responsibilities. China, the world’s top CO2 emitter has frequently been questioned about its data transparency and accuracy of energy and emission statistics. China implemented a top-down statistical system where energy statistics are compiled under the aegis of the National Bureau of Statistics (NBS) at the central government level, which oversees and coordinates the corresponding statistical departments at provincial and county levels8. The NBS publishes annually both national and provincial energy statistics. We compile the CO2 emission inventories for China and its 30 provinces for the period 1997–2010. However, CO2 emissions calculated on the basis of the two publicly available official energy data sets differ by 1.4 gigatonnes for 2010. The figure is equivalent to Japan’s annual CO2 emissions, the world’s fourth largest emitter, with 5% of the global total. Differences in reported coal consumption in coal washing and manufacturing are the main contributors to the discrepancy in official energy statistics. This paper presents an initial step to share and validate data and discuss methodologies in full transparency towards better energy and emission data for China.