This article attempts to analyse the role that the Rothschild House played in the evolution of Spanish Public Finances along the 19th Century. Therefore, it endeavours to describe an elementary chronology of the relationships between the Spanish Government and the Rothschild House during the whole Century, analysing the main financial operations they underwrote, quantifying their annual aggregate figures and, finally, trying to comment upon the different consequences of the process above mentioned. To cover these aims, we have deployed original records from the Rothschild Archives in London and Paris, their contents having been supplemented with information from National Public Records in Spain and France, and other financial institutions, namely the Bank of Spain.