Bourdais won just six points in 27 races for Toro Rosso
Toro Rosso have sacked French driver Sebastien Bourdais after two seasons with the team.
The Frenchman was overshadowed on his debut last year by German Sebastian Vettel and has been out-performed by Swiss rookie Sebastien Buemi in 2009.
Spain's British Formula Three champion Jaime Alguersuari is expected to fill the seat from the next race in Hungary.
"Sebastien's second year with us has not met our expectations," said Toro Rosso team boss Franz Tost.
"Therefore we have decided to replace him as from the next round of the world championship, the Hungarian Grand Prix."
French Rally driver Sebastien Loeb, 35, has been linked with a move to Toro Rosso from the World Rally Championship, although he would be unlikely to make any switch until next season.
The five-time World Rally Championship winner, who is currently second in the standings after eight rounds, is due to end his campaign five days before the final weekend of the 2009 F1 season.
Bourdais made his name in the United States, winning four successive Champ Car titles from 2004 to 2007 - the first driver in history to do so.
However, despite a promising start to life in Formula 1, the 30-year-old failed to live up to expectations picking up just six points from 27 races.
Alguersuari is a product of the Red Bull Young Driver Development programme and, if he does fill the seat vacated by Bourdais in Hungary on July 26, he will become the youngest driver in the sport's history at 19 years and 126 days.
"He's a very good driver," Alguersuari said of Bourdais on Monday.
"But it looks like this year he hasn't given it his all like he's supposed to give.
"I sincerely believe that Red Bull's decision is just, but it's never good to see someone taken off the team halfway through the season."