Using hydroxyl-containing olygoketones with different condensation degrees and dichloranhydrides of isophthalic and terephthalic acids, polyetheretherketones (PEEK) were synthesized by means of acceptor-catalytic polycondensation, and their properties were investigated. It was shown that PEEK possesses a better solubility, a higher molecular weight and is characterized by high thermal and mechanical properties. The correlation between some properties of polyethers and the degree of condensation of olygoketones was also investigated.