The article contains six letters by Russian orientalist Palladius (Kafarov) (1817–1878) to the Russian diplomat, scientist and traveler Fyodor Romanovich Osten-Saken (1832–1916). Palladius’ letters were written between 1867 and 1875. They were found in the Russian State Archive of Ancient Acts (Moscow). These letters were written during the period when Archimandrite Palladius directed the XV Russian Spiritual Mission in China (1864–1878). The letters contain information about the scientific research of Palladius, the ordinary life of Russian diplomats and of foreign scholars and missionaries in China. The first letter contains information about the publication of various materials related to the history of Russian-Chinese relations, including the Chinese embassies to Russia in the eighteenth century. The second letter contains information about the work of the English sinologist Joseph Edkins (1823–1905) and two American sinologists William Alexander Parsons Martin (1827–1916) and Samuel Wells Williams 1812–1884). The third letter informs about the trip of Chinese dignitary Binh Chun (斌 椿) (1804–1871) to Europe. The fourth letter describes various household details and changes in the Russian Diplomatic Mission in China. The fifth tells about the compilation of Palladius’ comments on the “Journey of Marco Polo”. The sixth letter describes the transfer of two letters received from the Chinese during Nikolai Spathari’s embassy (1636–1708), and Palladius’ research on the presence of Russians in the Ming China. The pages of the letters also mention the Sinologists Vasily P. Vasilyev (1818–1900) and Emil V. Bretschneider (1833–1901); traveler and geographer Mikhail I. Venyukov (1832–1901); Russian diplomats Alexander G. Vlangali (1824–1908) and Eugene de Bützow (1837–1904). Letters are published for the first time.