He has authored historical essays about the origins of the Spanish Civil War, the Second Republic in Spain, Francoism and the various political movements of that era.

Following the death of Franco and the reinstatement of a democratic regime in Spain, a slow process of opening of archives and publicizing of Civil War related documents began.

[1] In the face of this process Moa started reviving the Francoist theses that the parties that formed the Popular Front were ultimately responsible for the Spanish Civil War and the rise of autocracy in Spain.

Moa maintains that they have left a legacy of "moral, political and intellectual devastation", accuses the left of hypocrisy in regards to democracy and totalitarianism and claims that the material aid provided by Stalin and the Soviet Union to the Spanish Republic in the Civil War not only prolonged the war and caused innumerable deaths but also was equivalent to the help provided by Nazi Germany and Fascist Italy to General Franco.

[3] He has also written essays on Feminism, Marxism, current Spanish politics and an autobiographical book about his experiences in the terrorist group GRAPO.