Williams will try out German Nick Heidfeld and Britain's Anthony Davidson next month as they look to finalise their driving line-up for next season.
The British-based team have a vacancy after their bid to secure Jenson Button's services ended in failure.
Britain's David Coulthard is also thought still to be in contention.
"These tests are intended to assist the process of determining the team's full driver line-up for 2005," said a statement from Williams.
Davidson, who was BAR's test driver last season, will be given a drive at Jerez on 1 December, while Jordan driver Heidfeld will test at the same circuit on 9 December.
Williams' current test driver Antonio Pizzonia will also be given an opportunity in Barcelona on 24 November.
But the hopes of Sebastien Bourdais, who won the Champ Car title at the weekend, to secure a Williams drive appear to be over.
Williams lost both of last-season's drivers - Ralf Schumacher and Juan Pablo Montoya - to F1 rivals, with Mark Webber already confirmed as one replacement.
Montoya has joined McLaren, with Schumacher going to Toyota.