Yves Klein's Ex-voto Dedicated to Saint Rita of Cascia is a deeply spiritual and artistic gesture, highlighting Klein's engagement with themes of immateriality and faith. In 1961, Klein created this ex-voto, a votive offering, and secretly deposited it at the monastery of Cascia, where the relics of Saint Rita, the patron saint of lost causes, are preserved. The artwork comprises pure pigment, gold leaf, gold ingots, and a manuscript enclosed within a plexiglass container. This ex-voto was a token of Klein's gratitude to Saint Rita and was rediscovered fortuitously years after his death, during a restoration necessitated by earthquake damage in 1979​ (Yves Klein)​​ (Yves Klein)​.

Klein's devotion to Saint Rita was a significant aspect of his spiritual life, inspired by the popular cult of the saint in his native city of Nice. Before this ultimate offering, Klein had made several pilgrimages to Cascia, seeking Saint Rita's intercession in critical moments of his career. The ex-voto itself was designed to represent Klein's artistic and spiritual offerings, containing elements symbolic of his iconic International Klein Blue (IKB), pink pigment, and gold—materials that feature prominently in his work. The gold ingots in the ex-voto represented the first sales of Klein's Zones of Immaterial Pictorial Sensibility, with the agreement that if the buyer of a zone was willing to burn their certificate of ownership, all the gold would be returned to the cosmos​ (Yves Klein)​.

This act of faith and artistic expression encapsulates Klein's innovative approach to art, blending his Nouveau Réalisme style with profound spiritual undertones. Klein's engagement with spirituality and the immaterial is evident in various aspects of his work, including the Ex-voto Dedicated to Saint Rita of Cascia. Through this and other works, Klein explored the invisible, the void, and the infinite, constantly challenging the material confines of traditional art​ (TheCollector)​.