The film will be ready for release on May 1, 2014.
Hrithik and Katrina will undergo training for their respective roles, said a source, and the movie is likely to have an aggressive marketing campaign.
A Fox Star Studios production, Bang Bang will be directed by Siddharth Anand of Bachna Ae Haseeno, Salaam Namaste and Anjaana Anjaani fame.
The film will be shot across Europe, Far East and India, and is said to feature "spectacular stunt sequences, intense chemistry and edge-of-the-seat excitement, as Hrithik and Katrina will scorch the silver screens in never-seen-before avatars", said a statement.
The screenplay of the movie has been written by Sujoy Ghosh, and Suresh Nair and Abbas Tyrewala have penned dialogues for it.
The music for the film will be composed by popular duo Vishal-Shekhar.