One of the central projects of Rio de Janeiro´s City Government is the reduction of greenhouse gas (GHG) emissions in the city. With the Rio 2012 and 2016 Strategic Plan, the Municipal Climate Change and Sustainable Development Law (no. 5248/2011) and the Rio Low Carbon City Development Program (LCCDP), a set of coordinated planning tools has been developed for defining sustainable and low-carbon goals and implementing concrete mitigation actions within the city. Within these strategies, Rio has also prepared a detailed GHG inventory, and developed a basic tool to calculate GHG emissions of a city in a consistent way and to identify the most effective GHG mitigation actions. Rio already has much experience in performing GHG inventories: In 2013 the city finalized its third GHG inventory (2012) by applying and testing the new global inventory standard of the Global Protocol for Community-Scale GHG Inventories (GPC). The Protocol was developed by the World Resource Institute (WRI), the C40 Cities network and ICLEI. Thus Rio de Janeiro has become a pioneer in applying one of the newest GHG inventory schemes currently available.