The Swiss firm, Stadler Rail Group, has won a contract to supply 30 commuter trains for Hungary's state-owned railway authority MAV.
The deal, which was signed on Monday, puts an end to a drawn-out bidding war with Canadian competitor Bombardier.
The contract includes an option for the delivery and maintenance of an additional 30 trains for the Budapest region.
It is worth about SFr700 million ($558.6 million), Stadler said in a statement on Monday.
The company said it was pleased to win the tender after a long bidding war with Canadian rival Bombardier.
Stadler was awarded the contract on two previous occasions, but the decisions were thrown out by the public procurement authorities for irregularities.
Bombardier had reportedly threatened to close its factories in Hungary if it was not awarded the contract.
The Stadler Rail Group, which is owned by Peter Spuhler, a parliamentarian for the rightwing Swiss People's Party, is a family-owned joint-stock company.
It employs about 1,200 people at factories in eastern Switzerland and in the German capital, Berlin.
In 2004 its consolidated turnover reached SFr556 million, according to the company website.
Stadler focuses on the regional and suburban service market segments and claims to be the world number one in the cog-railway vehicle sector.
The firm said it had already sold 133 commuter trains of the make, Fast Light Innovative Regional Trains (Flirt), since last autumn. The railway vehicles which will be delivered to Hungary are built at a site in Berlin.
Stadler also delivered 42 commuter trains to the Swiss Federal Railways including an option for an additional 58 vehicles.
swissinfo with agencies
Stadler supplies 30 commuter trains for Hungary's railways.
The contract is worth up to SFr700 ($558.6 million) and includes an option for an additional 30 trains.
Stadler has a workforce of 1,200 in Switzerland and Germany.