Former US Secretary of State Condoleezza Rice has teamed up with the Queen of Soul, Aretha Franklin, for a rare music performance in Philadelphia to raise money for charity.

They took the stage at Philadelphia's Mann Music Centre in a rare duet for Rice, the classically trained pianist, and Franklin, the soulful voice of a generation.

Their aim was to raise money for urban children and awareness for music and the arts.

Their appearance in the three-hour concert before an estimated crowd of 8,000 overflowed with Franklin's catalogue of hits and arias from the world of opera and classical music.

Rice, better known as a diplomat and national security adviser, played piano while Franklin sang her hit "I Say A Little Prayer" as well as "My Country 'Tis of Thee."

Earlier in the programme, Rice performed a selection from Mozart's "Piano Concerto No. 20 in D Minor" with the orchestra.

Rice said their plan to play together was borne of their mutual appreciation for music and determination to keep it near and accessible to children.