One of the most debatable topics in modern linguistics is the study of intercategorical relations between several related languages. These multidimensional linguistic phenomena include the verbal formations, the so-called «hybrid forms of verbs» (participles, transgressive, reflexive verbal nouns), which are on the border of several parts of speech displaying syncretism at the morphological, semantic and syntactic levels. The article defines the status of verbal nouns in Slavic linguistics. It describes the intercategorical links of verbal formations and characterizes their hybridity. It provides comparison of specific features of reflexive verbal nouns in Slavic languages, including word-forming, morphological and semantic aspects. It also analyzes the use of reflexive verbal nouns in modern texts. Verbal nouns are a special hybrid form of the verb, which covers the features of diametrically opposite parts of the language, namely the noun and the verb. Reflexive verbal nouns are a specific feature of Polish, partly Czech and Slovak as well, which maintain the category of aspect and reflexivity. The postposition of the reflexive formant się, as well as the phenomenon of haplology and omission of się in lexicalized constructions mostly characterize reflexive verbal nouns. There are five groups of verbal nouns: 1) reflexive verbal nouns, in which the subject is the object of the action being performed as well. The reflexive deverbatives include words that denote the action directed at the appearance or surface of one’s body; 2) reciprocal verbal nouns, which denote the mutual (symmetrical) action of the subject and object against each other; 3) medial verbal nouns, in which the reflexive formant does not perform an independent function, but forms an inseparable unity with the noun and is a component of a non-permanent verbal lexeme; 4) terminative verbal nouns expressing a high degree of intensity, limit or achievement of the result of the action performed; 5) decausal verbal nouns describing situations that arise spontaneously, unconsciously, and are primarily typical for scientific literature. Decausatives state the change in the subject’s state, although the reason for this change remains unclear. The use of verbal nouns in Polish is characterized by high productivity, as evidenced by the formation of entirely new lexemes from loanwords used to denote modern information processes, and some formations even take on specific Polish reflexive features.