The muralist, printmaker, painter, teacher and political activist, was the youngest of eight children born in Mexico City in 1902 and orphaned when he was just two years old. Following his basic education, he enrolled in the the San Carlos Academy of Fine Arts, where he studied with Herran, de la Torre, and Rosas, among others. Mendez continued his studies at the impressionist Escuela de Pintura al Aire Libre founded by Alfredo Ramos Martinez.

In the years following his graduation in Mendez earned his living as a commercial artist, art teacher, and freelance illustrator for journals and liberal publications.

He was a founder of the Liga de Escritores y Artistas and as a co-founder of the famous Taller de Grafica Popular, the cooperative workshop established to educate ordinary people in the techniques of printmaking as an instrument of individual creativity, dignity, and political enlightenment. He joined The Stridentists, a group of creative talents in many fields who championed goals similar to the Dada movement in Europe.

Mendez was internationally recognized for his art and activism. He received many awards and appointments including a Guggenheim Fellowship for travel and study in the U.S.; the International Peace Prize in Vienna; was appointed from Mexico to the World Congress of Intellectuals for Peace in Poland; and the Posada Prize for Printmaking at the Second Inter-American Biennial of Painting, Printmaking, and Sculpture, among others. He died in Mexico City