According to the official statement, this will be effective from 06:00 on May 13 until 12:00 at night on May 14.
The president decreed the official mourning once the rescue and salvage actions were completed in the vicinity of the damaged hotel.
Cuba has so far reported 45 deaths, including a Spanish citizen, and almost a hundred injured.
Rescuers and firefighters today found the lifeless body of the last person to be identified as missing after the explosion.
During the validity of the official duel, the Cuban flag must be raised at half-staff in public buildings and military institutions.