In the year 2015 the Polish Institute of World Art Studies, together with the National Museum in Kraków and the National Museum in Warsaw and with the collaboration of the State Tretyakov Gallery in Moscow, undertook new research into the work of Henryk Siemiradzki, a distinguished Polish painter who was also associated with Russian and Italian artistic circles.\nThis five-year project, financed by the Ministry of Science and Higher Education within the framework of its “National Programme for the Development of the Humanities”, has borne fruit with the publication of the two-volume Polish and English Henryk Siemiradzki: Catalogue Raisonné of the Paintings, embracing paintings as well as drawn sketches and oil studies associated with them.\nThe ideal of those realising the project was to include in the Catalogue Raisonné all surviving works and those known from documentation, whose authenticity has been confirmed by means of drawings and sketchbooks, graphical reproductions and archival photographs from his studio, and finally by means of technical examination. The compilers of the Catalogue Raisonné put together a bibliography and information on the presence at exhibitions of each painting, they collected letters and other sources, established its history, and presented its iconography, in order to ultimately undertake an attempt at interpreting the work against the background of Siemiradzki’s creative work, as well as the artistic and intellectual currents of the period. The Catalogue Raisonné has been divided into sections covering a variety of thematic fields, with regard to scenes from history, religious representations, genre compositions, ceiling-paintings and theatrical curtains, and finally portraits and landscapes. This arrangement has, however, also been supplemented by a chronological survey of the work.\nThe third volume, Głosy o twórczości Henryka Siemiradzkiego (Voices on the Work of Henryk Siemiradzki – an Appendix), in Polish, contains a list of archival sources and a bibliography, together with studies on the work and artistic activities of the artist. The fourth volume, Warsztat malarski Henryka Siemiradzkiego (Painting Techniques, Materials, and Creative Process of Henryk Siemiradzki), also in Polish, has been devoted to technical examinations and the technology of the artist’s works. The result of the project is also the documentation of his life and art, the editing of his correspondence, and researches into the press, catalogues and publications. The results of these researches have been included, among others, in four published volumes of studies, the fruit of international conferences, including in Warsaw in 2017, in Kraków and in Rome in 2018.\nThe realised project opens up new perspectives of research, not only into the painted work of Siemiradzki, but also into Polish and European art of the second half of the 19th century.