This article deals with the process of the establishment of Russian-Spanish relations in the 18th century and the role of one of the most distinguished Russian diplomats at the court of Catherine II Stepan Zinoviev who spent in Madrid around 20 years (1772-1794). The study is based largely on manuscripts (diplomatic and other correspondence) from the Archives of the External Policy of Russian Empire in the Ministry of Foreign Affairs of the Russian Federation and fills a gap in the investigation of Russian foreign policy of the 18th century and the Russian-Spanish relations. Catherine’s foreign interests were focused toward the major states of Northern Europe, but she also tried to strengthen the position of Russian Empire in Europe, to embed the country in the European 'Balance of Power' by establishing diplomatic relations with all European countries. In this sense, the Iberian Peninsula was not wholly without significance for Russia. The political unions of Russia with the outlying countries, as Spain, depended not only on the international situation in Europe in the second half of the 18th century but on the image of the country that was created by Russians who visited Spain at that time. The position of diplomats was particularly important they were almost the only ones, except for merchants and sailors, who visited that country and it is on the basis of their reports Russia's foreign policy in relation to Spain was built in the 18th century. Based on the reports of Zinoviev we can reconstruct the images of such important political figures as the Spanish King Charles III, Secretary of State Count of Floridablanca and the other ministers of the Spanish government. The biography of the outstanding Russian diplomat Stepan Zinoviev is presented in this article for the first time.