The thesis explores the content and characteristics of separate works on logic written by Croatian thinkers during the 19th century. During this period, the following nine Croatian logicians wrote or prepared eleven works dedicated to this philosophical discipline: Pietro Bottura (1779–1861), Vatroslav Bertić (1818–1901), Juraj Pulić (1816–1883), Vinko Pacel (1825–1869), Josip Glaser (1842–1920), Gjuro (Đuro) Arnold (1853–1941), Albin Nađ (1866–1901), Gavro Manojlović (1856–1939) and Franjo Marković (1845–1914). All their works belong to the genre of textbooks or manuscripts intended for secondary school or university teaching. The works were dominated by the material belonging to traditional logic, with a special emphasis on its scopes derived from the teachings of German, but also English and French logicians from the 18th and the 19th centuries. There is also content that belongs to mathematical logic, firstly only in hints in Bertić’s work and then in the form of criticism in Marković’s manuscript, while it is fully evident in Nađ’s textbook in the Italian language. Besides mathematical logic, other then contemporary endeavours are discernible in the works on logic in Croats during the 19th century, especially those pertaining to the theories of judgment, more precisely to the discussion of the components of that logical form of thinking. A logical approach to language issues is also noticeable, which gave rise to the topics belonging to the philosophy of language in general, and logical semiotic in particular, which also means that those issues anticipated topics that became a part of the focus of logical discussions in the decades to follow. The works on logic from the pens of Croatian thinkers in the 19th century not only reveal the richness of the conceptions of logic represented in them (formalistic, real, formal-real, psychologistic, Neo-scholastic) but also attest to numerous examples of their permeation. When it comes to narrower logical problems, the correspondence theory of truth prevailed in the Croatian logical heritage of that period. Moreover, Croatian logicians showed the knowledge of the history of logic, both in its presentations in separate chapters and in the logical material across their works. Besides the knowledge of history, they demonstrated the knowledge of the teachings of their contemporaries, approaching them mostly affirmatively but sometimes also critically. Croatian logicians from the 19th century also offered new logical contents in their works, which were in many cases represented in the works on traditional logic published in Croatia during the 20th and the 21st centuries. In addition, they devised new terminological solutions for logic in the Croatian language, which were less accepted and applied in later works, certainly as the result of the changes in the linguistic and political circumstances in Croatian history. In the end, in their works, they established methodological and didactic standards for learning and teaching logic that particularly relate to exercises, examples and explanations of various procedures. All that also means that the features of the works on logic by Croatian thinkers of the 19th century largely coincide with the features of the European logic of that period. The characteristics of nineteenth-century Croatian logic also derive from those conclusions. The nineteenth-century Croatian logic is marked by the systematisation of material within secondary school and university literature. Furthermore, it influenced Croatian logic in the 20th and up to the present part of the 21st century, as its material was the backbone of later textbooks in traditional logic to a significant extent. In addition, it is characterised by the search for Croatian terminological solutions for international logical terminology. Even though few of those solutions were applied in later works, they were still an incentive that resulted in the establishment of logical terminology in the Croatian language. Nineteenthcentury Croatian logic followed the directions of the development of European logic of that period, laid the foundations of logic in the national language and greatly contributed to the development and recognition of logic in Croatia.