"She spoke her mind," Francis told the Albanian priest acting as his interpreter during the visit yesterday, according to papal spokesman Federico Lombardi.
The pope met the late nun, an ethnic Albanian from Macedonia, in Rome in 1994 when he was mere Bishop Jorge Mario Bergoglio.
Lombardi said the pope recalled admiring "the strength and the decisive character of her involvement".
"I would have been scared if she had been my mother superior," he told the priest.
She died in 1997, and was beatified in 2003.