He was born on June 4, 1877, in Quito. His parents were Ángel Adolfo Páez and Rita Lemus Chávez. After his parents’ divorce, he changed his second surname to that of his maternal great-grandfather. Páez studied at the Lycée Hoche in Paris and pursued engineering at the Universities of Ghent and Brussels in Belgium. He married Adelaida Espinosa García, and they had a daughter named Rita Páez Espinosa.