Rajoy and Mas have been engaged in a high-profile stand-off for some weeks but on Tuesday the two leaders finally agreed on a date to meet.
The Spanish PM will have home advantage with the meeting — his first with Mas in nearly a year — to take place at his Moncloa residence in Madrid on July 30th.
The meeting has been in the offing since the two men had a brief telephone conversation on July 11th but the two leaders have keep the Spanish press guessing as to the actual date for the sit-down.
The announcement of a date is seen as a breakthrough as Rajoy and Mas attempt to end the deadlock over the issue of a unilateral vote on the issue of independence of Catalonia.
Mas has been pushing hard for a non-binding November 9th referendum which would test the level of popular support for the idea of Catalonia leaving Spain, despite the national parliament in Madrid ruling the move illegal in April.
In recent times, however, Mas has shown he may be willing to budge on the details, hinting during an interview with the business paper Bloomberg that postponing the vote might be an option.
Rajoy has, for his part, suggested Madrid may be willing to rejig the country's system for financing its regions so that rich players like Madrid and Catalonia don't see as many of their resources syphoned off to subsidize the country's poorer areas.
Proud of their distinct language and culture and fed up after five years of economic crisis, many of the 7.5 million people in Catalonia want to leave Spain, saying they feel short-changed by the central government which redistributes their taxes, and which ignores their separate identity.
The European Union has previously said that an independent Catalonia would be forced to leave the EU, and would have to reapply for membership.