In the bacterial culture of C. eutrophus B10646 in the synthesis mode of reserve polyhydroxyaleanoates when included in the growth medium, in addition to the main substrate of glucose, substrates-precursors of various monocarboxylic acid monomers - salts of valerianic and hexanoic acids, pripionate, γ-butyrolactone, a family of three and four-component with a different set and ratio of monomers and studied the physico-chemical properties. The three-component samples were formed by monomers of 3-hydroxybutyrate (3HB), 3-hydroxyvalerate (3HV), 4-hydroxybutyrate (4HB) or 3-hydroxyhexanoate (3HB) and had the following compositions: P(3HB/3HB/4HB) and P(3HB/3HV/4HH); the four-component copolymers P(3HB/3HV/4HB/3HH) contained a set of 4 monomers. All copolymer samples, regardless of the composition and ratio of monomers, had lower molecular weights and higher polydispersity values compared to the highly crystalline homopolymer 3-hydroxybutyrate, but retained thermal stability properties, having a gap between the melting point and thermal degradation of at least 100-110 ° С . The inclusion of monomers in the C-chain of 3HB monomers 3HV, 4HB and 3HH caused a change in the ratio of crystalline and amorphous phases, and a decrease in the degree of crystallinity (Cx), depending on the type of monomers and the content in the copolymer. The maximum decrease in Cx (up to 9-17%) was recorded in three-component samples P(3HB/3HV/4HB) and up to 30-36% in four-component copolymers P(3HB/3HV/4HB/3HH). The possibility of synthesis of polymers of various compositions, significantly differing in basic properties, is proved.