The 114m-long six-car trains will each accommodate up to 1200 passengers and will be formed of four powered and two trailer vehicles.
CAF was selected as preferred bidder in October and beat off competition from Bombardier, which has supplied 44 Movia trains to Metrorex since 2001. The contract represents CAF's first rolling stock order in Romania.
Construction began in April on the initial 6.1km section of Line M5 between Parc Drumul Taberei and Eroilor, which will open in 2013. In the longer term, extensions to Pantelimon and Piata Iancului are planned.
The EIB has provided a Euros 394m loan to help finance the new line, which includes Euros 54m towards the cost of rolling stock.