Santillán returned to post-Franco Spain in 1977, at the age of 80, settling once again in Barcelona, and producing a final memoir, Memorias 1897–1936 (1977). He died in Barcelona on October 18, 1983.

Literature

Santillán's works include:

• Ricardo Flores Magón: el apóstol de la revolución social mexicana, (Ricardo Flores Magón: Apostle of the Mexican Social Revolution), Mexico City: Grupo Cultural "Ricardo Flores Magon", 1925
• El anarquismo en el movimiento obrero, (Anarchism in the Labour Movement), (with Emil