The British star was looking dapper in a morning suit and top hat to film his new project Bel Ami in Budapest.
In the new flick he plays journalist Georges Duroy, a handsome young man who rises to a position of power in 19th century Paris by seducing some of the city's most powerful, intelligent and wealthy women.
Out next year, the film - which is adapted from the classic novel by French author Guy de Maupassant - also stars Uma Thurman, Kristen Scott Thomas and Christina Ricci.
Rob was also spotted, this time minus his costume, as he left the set after wrapping up filming for the day.
After completing the Budapest shoot he'll be heading to London, where further scenes for Bel Ami will be shot for another two weeks.