Abstract <p>Propylene polymerization titanium–magnesium catalysts in the presence of ethers are synthesized. It is shown that aliphatic ethers and 1.1-diethers are participated in the formation of magnesium chloride although they are not contained in catalysts. Aromatic ethers (except methyl phenyl ether) are ineffective in the MgCl₂ formation. Subsequent adding of the phthalate (DBP/Mg = 0.05 mol) lead to the synthesis of the phtalate titanium–magnesium catalyst which in the case of aliphatic ethers and 1.1-diethers have catalytic properties higher than the titanium–magnesium catalyst for comparison (DBP/Mg = 0.05 mol) and close ones (for some ethers) to the standard titanium–magnesium catalysts (DBP/Mg = 0.2 mol). Comparative analysis of the composition of phthalate titanium–magnesium catalysts prepared using ethers or ketones and X-ray data indicate a close size of MgCl₂ crystallites in both cases. The composition of titanium–magnesium catalysts synthesized in the presence of ethers is consistent with the distribution of dimeric TiCl₄ complexes alternating with chlorine vacancies (…□TiTi□TiTi…) on the lateral cuts 104.</p>