Núñez, formerly head of franchises for fast food chain Mar del Plata, became a stop gap spokesman earlier this year following an E coli bacteria scare. He will work alongside Molaro until the end of the year.
Molaro, who is stepping down from hypermarket chain Carrefour, arrives at a time of significant management change at the McDonald's. Vice chairman and head of operations José Fernàndez takes charge of general management for Argentina, and Woods Staton becomes regional CEO.
Molaro is to lead a review of external PR consultancies. He will also be involved with institutional relations following the resignation of Maria Jose Parodi.