Using oligoketones with different degrees of condensation (n = 1, 10, 20), dichlorides of isophthalic and terephthalic acids and 2,2-bis[4-hydroxyphenyl]-propane block-copolyetherether ketones (BCPEEKs) were synthesized by means of acceptor-catalytic polycondensation. Their properties were also investigated. It was shown that BCPEEK possesses good solubility, high molecular weight, and is characterized by high thermal and mechanical properties. The correlation between some properties of the polyethers and the degree of condensation of oligoketones was also investigated.