Her first major international success came at the Royal Opera House, Covent Garden, where on November 5, 1868, she made her London debut as Azucena in Il trovatore, also by Verdi.

Scalchi helped to make history when she sang in the newly constructed New York City Metropolitan Opera's first ever staged work, Charles Gounod's Faust, which inaugurated the theatre on October 22, 1883.

She appeared, too, in the initial American productions of Amilcare Ponchielli's La Gioconda and Umberto Giordano's Andrea Chénier.

Scalchi retired from the Met in 1896 and formed her own private company of singers a year later, which then undertook a final American tour.

Commentators praised Scalchi during her prime for the strength, wide range and remarkable agility of her voice, although she was said to have possessed distinct breaks between each of her registers.