Since China has put forward a series of obligatory Greenhouse Gas (GHG) emission reduction targets, provincial governments have issued provincial-level "Twelfth Five-Year" carbon intensity (CO2 emissions/GDP) reduction targets. There are 653 cities distributed throughout the eastern, middle and western parts of China, and each region has different quotas and paths to reduce GHG emissions, while the western part has greater challenges than the others. This paper predicts CO2 emission reduction potential of Chongqing, assesses the difficulty of achieving its CO2 emission reduction targets, and analyses its low-carbon transition path. The results show that the carbon intensity of Chongqing in 2020 will range from 1.58 to 1.75 ton CO2/10(4) RMB, and there exist some scenarios with strong potential to meet carbon intensity reduction targets for 2020. Improved technology, energy efficiency, the optimization of energy input mix, and the adjustment of industrial structure are suggested to be major strategies to reach Chongqing's carbon intensity targets. (C) 2015 Elsevier Ltd. All rights reserved.