Castañeda was a disciple of José María Zumalacárregui, Antonio Flores de Lemus and F. Heinrich von Stackelberg. He studied law at the University of Valencia, where Zumalacárregui headed the Department of Economics and Public Finance at that time. Castañeda graduated in 1920 and moved to study at the School of Industrial Engineers of Madrid, in which he served as professor after graduation. He joined the corps of Industrial Engineers serving in the Tax Office at the same time as he attended Flores de Lemus’ lecturers. In 1934, Flores de Lemus appointed him assistant professor, remaining in that position until the outbreak of the Civil War.

Castañeda was purged after the war as he had the rank of Commander in the Republican army. Since he was a member of the General Commission of Electricity of the Republic, he belonged to the group of economists of the Institute of Political Studies from 1940.

Castañeda joined the Faculty of Political Science and Economics as a lecturer in 1944 and built a successful academic career for almost thirty years. In October of 1945, he held the chair of Economic Theory remaining in this position until his retirement in 1970.

Prior to his expulsion from the Faculty of Political Science and Economics in 1969, he held the position of Dean during a difficult period of student protests, between 1964 and 1967. Castañeda introduced Econometrics in Spain and was director of two academic publications: Journal of Applied Science and the Journal of the Institute for Rationalization of Labour.

In 1956, he held membership in the Royal Academy of Moral and Political Sciences, in which he would regularly give presentations for nearly thirty years. Among his books are “Consumption of Tobacco in Spain and Associated Factors” (1945), and especially “The Lessons of Economic Theory, Consumption, Production, Prices and Incomes” (1968). In 1970, he was appointed Honorary Dean of the Complutense University of Madrid.