Artur Mas' Catalan nationalist CiU bloc was expected to win the regional race late Sunday. Exit polls showed the CiU winning between 63 to 66 seats in Catalonia's regional parliament with the incumbent Catalan Socialist Party (PSC) getting between 24 and 27 seats.
CiU campaign manager David Madí called it an "historical victory" for the bloc, which will put an end to José Montilla's current PSC-led coalition.
Voter turnout for Sunday's election was slim, according to some estimates. An estimated 5.3 million people were eligible to vote in the regional race, in which local municipal leaders were also elected.
The PSC has governed the region for seven years and the CiU had held power for 23 years until 2003. Many analysts believe that today's vote will be seen as a punishment vote for Prime Minister José Luis Rodríguez Zapatero's Socialist government if the PSC is thrown out of office.
Shortly after the polls closed, a man threw an egg at PSC spokesman Miquel Icetas during a news conference.