AbstractPoly(oxovinyl sulfide)s3were prepared by vinylogous nucleophilic substitution polymerization of bis(3‐chloroacryloyl) derivatives of benzenes (1aand1b) with 4,4′‐oxydibenzenethiol(2). The synthesis involves solution polycondensation and two‐phase polycondensation with phase transfer catalysts. Polymers having inherent viscosities in the range of 0,2–0,7 dl·g−1were obtained quantitatively by both methods. They are soluble in concentrated sulfuric acid, dichloroacetic acid, andm‐cresol, and practically insoluble in polar aprotic solvents and common organic solvents. Thermogravimetric studies in both air and nitrogen atmospheres indicated that the decomposition temperatures for 10% weight loss of the polymers we