The 25km east-west line with 20 stations links Tláhuac with Mixcoac and interconnects with lines 8, 2, 3 and 7. Completion of the project has expanded the network to 226km with 195 stations.

Line 12 cost Pesos 24bn ($US 1.85bn) to construct and equip, with the federal government contributing Pesos 13.2bn. CAF has supplied a fleet of 30 seven-car trains under a €1bn 15-year deal which covers supply and maintenance. Alstom electrified the line and installed its Urbalis Communications-Based Train Control (CBTC) system which enables automatic operation.

Mexico City commuters are able to ride Line 12 free-of-charge until Sunday November 4 to allow them to familiarise themselves with the new metro line which serves the southern part of the city.