Desiro is a brand name of modular trains manufactured by Siemens of Germany.

Light train

The most common variant can be built as a diesel or electric multiple unit (DMU or EMU). It is used in Austria, Germany, Romania, Czech Republic, Denmark, Slovenia, Greece, Malaysia, Bulgaria and Hungary. Although there are various differences between these trains, the body design is the same.

These trains are mostly used for regional services. They are part of a new generation of light, modular trains which have become widespread in many European countries; sometime referred to as light train . These trains are relatively cheap to build and operate. Fast acceleration makes them suitable for train services with a short station distance. However, they are sometimes criticized for their lack of passenger comfort.

Desiro UK

Siemens uses the name Desiro UK for new EMU trains used by South West Trains in the United Kingdom. These trains have a completely different design.

Desiro are used in the UK on South West Trains which has 45 x Class 444 five-car units and 120 x Class 450 four-car unit, all 750V DC power supply, running from Waterloo to Alton, Basingstoke and the Hampshire/Dorset coast.

They are also in use from London Liverpool Street to Clacton/Walton and Ipswich, which has 21 x Class 360 four-car units running on 25KV overhead supply.

Thirty four-car Class 350 25KV overhead sets are under construction for service on the West Coast Mainline, including services from Euston to Northampton/Birmingham.

The trainsets have modern facilities, such as biological waste storage tanks, ergonomic seats and spoken announcements.

Desiro in Romania

Caile Ferate Romane (CFR), the national railway operator of Romania, is one of the largest users of Siemens Desiro trainsets (the light train variant). CFR, which is currently going through a process of modernisation to make it Eastern Europe's premier railway carrier, has bought many Desiro trainsets and uses them on Intercity (IC) routes, which serve as shuttles between main cities with very few stops and fast services. CFR is also planning to use them as part of a proposed commuter railway in Bucharest and Ilfov county. For more information on routes, see Caile Ferate Romane.