The relevance of the study of the history of null suffix derivation as an important component of the Ukrainian word-forming system is substantiated. The origin of Proto-Slavic derivatives is revealed with the help of thematic vowels *a, *ŏ, *and, *ŭ, which originally served as a means of noun word formation, their original meaning is no longer restored. It was found that the materially expressed suffixes in the Proto-Slavic language had a specific character, they combined two functions: word-forming and inflectional, which gave rise to call them suffixes-inflections or protonulsuffixal forms. Subsequent common language changes (phonetic, morphological) caused the loss of the material index of origin, while preserving the structural and semantic connections of creative and derivative formations. The description of lexical-word-forming types of null suffix masculine deverbatives in the ancient Russian-Ukrainian language of the XI–XIII centuries is carried out. based on the materials of the first written monuments of the Ukrainian language and lexicographical works that reflect the vocabulary of this period. The selected derivatives have a general word-forming meaning “carrier of a procedural feature” or “objectified action or state”. These groups of derivatives represent lexical-word-forming types of names of persons by permanent or temporary occupation or profession, names of persons-bearers of procedural attribute (behavior, views, family relations, social status, etc.), names of subjects of action as a collective concept. Several attributive names of animals, less often of plants, have been documented. Lexical-word-forming types of null-suffix derivatives in the word-forming field of inanimate objects are described: natural phenomena, natural disasters, names of natural objects, locatives, structures, tools, results of physical or intellectual action, etc. In the group of derivatives with the general word-forming meaning “objectified action or state” groups of derivatives are analyzed, which name the action of greater or lesser intensity as an object, names of human actions (positive or negative) human feelings, desires, inner state, names of intellectual action processes. Selected linguistic facts give grounds to assert that the zero-suffix creation of masculine nouns in the ancient Russian-Ukrainian language was a common phenomenon, which laid a strong foundation for further activation of the zero formant in the noun derivation. Keywords: history of null-suffix derivation, pro-noun suffix formants, general word-forming meaning, lexical-word-forming types, carrier of procedural feature, objectified action or state.