The production and use of chemical weapons by the Spanish army during the so-called Rif War in Morocco, successfully concealed for over half a century, began to be exposed by international and Spanish researchers from 1990 and especially during the 2000s. Two main issues have been hitherto explored. On the one hand, the role of Hugo Stoltzenberg, a German chemist and industrialist who sold chemical weapons to Spain and directed the installation of a military toxic gas factory near Madrid. On the other hand, the types and quantities of chemical weapons produced in or purchased by Spain, the tactics of gas attacks and the military operations in which they were used in Morocco, including an evaluation of their eventual impact on the march of the Rif War and on the civil population’s health and living conditions. In this paper we will propose an updated reassessment of the question of chemical warfare in Morocco’s Rif War. On the one hand, we will point out the main gaps and inconsistencies of the prevailing historical narrative. On the other hand, we will present fresh research that will contribute to clarify hitherto unknown aspects of the question, including the mobilization of chemical companies, the use of toxic gases by the French army or the role of army health personnel and the risks to which they were exposed. For this purpose, we will use documentary evidence gathered at archives in Spain, France, and other European countries.