Since 2004 changes in the regulatory framework of the Chilean public and electricity sectors have been taken place (19940 law in March 2004). Transparency rules must be following by the market agents in pricing procedures of the electricity market. Consequently, technical, economical, and reliability data of the Chilean power system are available for simulation and optimization purposes. The Chilean Central Interconnected System (CIS), the largest and complex system in the country is selected as a test system. A description of the main characteristics of the system is presented. Technical and economical information is available in the IEEE PES test system homepage (http://www.ieee-tea.ethz.ch/wiki/Test_Systems). It is envisioned that the CIS-Test system can be used as a test bench for both economical and technical studies.