Radical Art Informel is one of the particularly important chapter in Croatian art of the late 1950s and early 1960s. By introducing new materials, artistic procedures, and materic experiments, radical Informalism epitomizes the critique of “traditional modernity”, especially that of figurative and mimetic art as well as a reaction to the advent of geometric abstraction. This thesis is concerned with the emergence, reception, interpretation, and definitions of radical Art Informel in the period from 1956 to 1962, as well as its influence on later art of the 1970s and 1980s. This work questions the shift in the perception of the very nature of painting and art through radical Informalist works, as well as of the main exponents’ role in the formation of the concept of the non-pictorial, non-semantic, and nonmimetic typology of Informalist painting within Croatian art history. A particular contribution which this dissertation aims to provide lies in the cataloging of previously-expounded-on artworks, their interpretation, as well as an extensive and exhaustive synthesis of the emergence of radical Art Informel in Croatian art based on previous theoretical, critical, and historic interpretations of this artistic phenomenon in Croatian art. By analyzing and comparing individual artworks of the protagonists of radical Informalism in Croatia, this work will identify their differences and similarities when compared to artworks of European and global Art Informel. In addition to this and alongside earlier theoretical and critical models which have been related to Art Informel in Croatia, this thesis provides some other possible interpretations of radical Informalism based on, for example, Rosalind Krauss and Yve-Alain Bois's concepts of entropy and the formless, the aesthetics of ugliness (Umberto Eco, Theodor Adorno, Karl Rosenkranz, Hal Foster, Jean Dubuffet, Georges Bataille), the notions of deformation and disfiguration or the ideas of Georges Mathieu on the negation of meaning and dissolution of shapes. Beside the aforementioned, this thesis regards and questions Informalist creation from other critical perspectives, such as that of gender theory. Apart from the oeuvres of the five protagonists (Ivo Gattin, Eugen Feller, Marijan Jevšovar, Đuro Seder, Vlado Kristl), this work also presents the individual poetics of seven artists who, in one phase of their artistic practice, created works of materic Informalism or approached radical Art Informel in several of their artworks (Božidar Jelenić, Tomislav Hruškovec, Ferdinand Kulmer, Miljenko Horvat, Josip Vaništa, Rudolf Sablić, and Frano Missia), all in the period from 1956 to 1962. Taking into consideration previous findings, archival resources, documentation and literature on the subject, as well as exhibition catalogs and some newer interpretations, this thesis also elucidates radical Art Informel through socio-political contexts according to which the reception of the radical type of Art Informel did not enjoy significant support from art institutions, nor did its main exponents have an equal social and art status as did individual artists of a pictorial, more moderate Informalist orientation. Furthermore, this work contextualizes radical Art Informel in Croatian art within the Yugoslav art scene of the time and as a component of global Informalist tendencies. It takes a critical stance towards the very thesis on radical Art Informel and questions the validity of its name and definition, providing additional interpretations and categorizations of Informalism within Croatian art history. The intention of this thesis is to contribute to the broader perception and understanding of the frameworks within which this artistic phenomenon appeared, as well as its unique positions and roles in the context of Yugoslav art, its disparities compared to other art centers of former Yugoslavia, and its similarities to some South European art centers. The intention is also to clarify the specific socio-political context and social status of these dissident artists within the framework of extrainstitutional support and opposition towards mainstream art movements. Subsequently, the work will provide morphological stylistic characteristics of the materic, or rather radical variant of Art Informel which is differentiated from works within the oeuvres of the artists that shall be covered here, compared to the more pictorial variant of Informalism. It will also compare these works with the works of Art Informel artists from Europe and around the globe. The term “Art Informel”, even in its formative years, implied a whole host of variations with differing characteristics and nominations. Shortly after they appeared in France, similar or equivalent phenomena started appearing in Germany, Spain, Italy, and other countries. One could have concluded that what was in question was a dominant art practice in post-war Europe. It therefore does not come as a surprise that this phenomenon appeared in Yugoslavia as well, which was a more liberal country in terms of its political convictions, and with more open borders compared to other European countries within the Socialist order. Up to this point, numerous critical texts and articles have been written on the topic of Art Informel, or more precisely that of the radical type of Informalism. It is also mentioned in the systematization of Croatian art of the 20th century, as well as within individual biographies of its most important proponents. However, within the literature to date, radical Informalism has yet to be the topic of a comprehensive monograph, though it presents an important segment of the national artistic patrimony and is of international import. Through a methodological approach, using various art-historical and hermeneutic methods, this thesis aims to question several hypotheses, the first of which being that radical Art Informel strives towards the negation of painting, or rather leans towards the concept of the anti-painting by making destructive and radical interventions in the material or matter, by researching and introducing new unconventional art materials, media, art processes, and pursuing the abolishment of the “beauty” of the painting. The second hypothesis would be that radical Informalist artworks possess fundamental stylistic, morphological, and discursive attributes of the non-semantic and antipictorial, which, on a formal level, are manifested in an abstract, mainly materic and monochrome painting style that, in some individual cases, transgresses the boundaries of the specificity of the medium, the two-dimensionality of the painting, and borders on sculpture (Gattin and Feller). The third hypothesis which shall be questioned is that radical Art Informel is predominantly present in the oeuvre of those artists who had not earned recognition on the art scene during the time of the appearance of Informalism, nor were they to be found within Masters’ Workshops. Rather, these were individual artists, members of groups such as Gorgona or artists close to this group, who took an antipainterly approach to art as well as a particular (outsider) existentialist outlook on life and artistic creation. The thesis is subdivided into several chapters. The first chapter provides insights into the various nominations (names), characteristics, and theoretical definitions of Art Informel, as well as its emergence in Europe and the world. Apart from France, Italy, Spain, and Germany, Art Informel and Expressionism appeared in Yugoslavia, as well as in individual Eastern European countries, and in the art of the United States, Canada, Japan, Argentina, and Brazil. As has already been touched upon, besides critical and theoretical models of interpreting Art Informel by Tapié, Mathieu, Argan, Dorfles, Crispolti, Barilli, Calvesi, and Eco, as well as interpretations of American action painting by Rosenberg and Greenberg, emphasis will be placed on the notion of the informe (that which has no form)—which Rosalind Krauss and YveAlain Bois adopted from George Bataille—and Rudolf Arnheim's entropy theory. Numerous other European theoreticians of Art Informel and Abstract Expressionism, such as Cirlot, Haftmann, Ragon, Restany, and others, are also mentioned. In addition, a short overview is provided of the time immediately preceding Art Informel, that is the socio-political situation and the attitude towards abstract art in Croatia and Yugoslavia during the 1950s and 1960s and towards the emergence of Informalism in the Yugoslav art scene. The second chapter deals with the emergence, reception, interpretation, and definitions of radical Art Informel. The heterogeneity of Informalist painting in Croatia encouraged Ješa Denegri, during the first significant retrospective of Art Informel in 1977, to develop the hypothesis of two disparate sides of Art Informel – the radical and pictorial type. Other divisions of Art Informel are also provided in this chapter, as well as critiques of the theory on radical Informalism and the conception of Informalist painting in a somewhat limited classification such as this. Over time, the notion of radical and materic Art Informel also became rooted within the annals of Croatian art, as is visible in newer systematizations of Croatian art of the 20th century. The third chapter of this thesis provides insights into Informalist art of the main protagonists of Art Informel and those artists who, through individual works, were brought closer to them by adopting similar practices and created artworks of similar morphological stylistic characteristics or shared the same opinions, ideologies, and viewpoints on art. In the subchapters that cover the diction of individual artists, a comparison is provided between specific examples of artworks that point to the similarities and differences between works of artists from Europe and around the globe, and those of the aforementioned protagonists of Croatian radical Art Informel. The fourth chapter is dedicated to the examination of radical Art Informel in the context of Yugoslavia, as well as to comparisons with the emergence of Art Informel in other countries (Serbia, Slovenia, Montenegro, North Macedonia, Bosnia and Herzegovina) with a particular emphasis on the differences and similarities of Informalism in Zagreb and Belgrade. Art Informel in Belgrade stands out because its critical and theoretical interpretations were clearly expressed even in the 1960s, at the time of the development of Art Informel, and primarily through the endorsing exhibition Young Painters of Belgrade as far back as 1962. Also, it had created a contentious atmosphere from the very start and was accompanied by numerous texts and reviews by the Serbian art historian and art critic Lazar Trifunović, who was a big proponent of Belgrade Art Informel. Art Informel in Croatia is an extremely complex and heterogeneous artistic phenomenon. Alongside general characteristics of Art Informel - the abolishment of traditional conceptions of composition and painting, the dissolution of mimesis, the use of free organic forms, and the use of non-painterly materials and procedures - all of these characteristics are even more pronounced in radical Informalism. In the morphological sense, they are embodied in an ever more pronounced materiality, reliefness (texturedness), formlessness, monochromatic and achromatic color registers, the use of raw materials, their coming into being through destructive, deforming processes such as carving, scratching, accumulating structures and masses, fragmenting, removing layers and burning, as well as in the representatives’ views on art: the negation of painting, a leaning towards anti-art, self-referencing, nonpicturality, nonsemanticity, nihilism, and a brutal aesthetic. The radical variant or type of Art Informel in Croatian art can also be called materic painting, materiologic or perhaps nonsemantic Informalism. This thesis provides insights into the differing contexts of radical Art Informel; from stylistic-morphological interpretations, theoretical-critical interpretation, the sociopolitical context, the aesthetics of anti-painting and the phenomenology of processuality, to scrutinizing the emergence of radical Art Informel within the discourse of gender theory.