Natural fine chalk (calcium carbonate) is widely used functional filler for composite materials used in many industries. The development of in-depth studies of the physicochemical properties of hydrophobic chalk contributes to the expansion of its application. The analysis of scientific and technical literature has shown that at the moment there are no studies of the parameters of the porous structure and textural parameters of natural chalk of various granulometric composition, especially superficially treated (hydrophobized) with fatty carboxylic acids. Carboxylic acids of C17 to C20 fractions are practically applied for hydrophobization of calcium carbonate that is conditioned by presence of these acids with enough long hydrocarbon chains and reactive carboxyl group. The treatment of chalk with hydrophobizing additive gives it the following advantages over untreated chalk: prevention of moisture accumulation, absence of caking and improvement of technological properties (flowability, compatibility with polymer and others). The paper presents the results of chemical and mineralogical analyses of natural chalk from the Sheinsky deposit, data on the differential distribution of particles, the degree of hydrophobicity, and the study of the textural characteristics of natural and hydrophobized fine chalk. The influence of the grinding method on the granulometric composition is evaluated and the cumulative effect of the grinding method and hydrophobization on the texture characteristics of chalk is revealed. It is established that the surface treatment of chalk particles with fatty acids (C18 content not less than 65 wt%) affects the process of nitrogen gas adsorption