The paper discusses the construction of the detailed inner and absolute chronology of the Koshylivtsy group of the Tripolye culture, existing in the 2nd half of 3rd Millennium BC and in the beginnings of the 2nd Millennium BC on areas of Western Ukraine.To this end the typological, stylistical and comparative analyses of numerous pottery forms, painted with black, red and white ornaments, and probabilistic analyses of some radiocarbon dates were carried out. Detailed analyses of ornament motifs and colour of used paints allowed to reconstruct the set of characteristic stylistic elements of the Koshylivtsy group. Owing to the comparison of some of these elements with similar ones from the other local groups of the Tripolye culture it was possible to determine their relative chronological position in the evolution sequence of the late phases of the mentioned culture. The Koshylivtsy group in its evolution passed through the following phases: (a) phase I (Werteba II - Bilshivtsy V) - the period of group formation. Strong Brinzeni and possibly Lublin-Volhynian influences, (b) phase II (Blyschanka) - strong influences of late-Shipentsy group, (c) phase III - (Koshylivtsy Camp) - simplification of ornamentation, (d) phase IV (Kudrynci, Kozyna) - further simplification of ornamentation.