Sulfonated aliphatic-aromatic polyester compositions having improved thermal properties, and articles such as films, coatings and laminates, produced from the sulfonated aliphatic-aromatic polyester compositions, are provided. Some of the films are biocompostable. Films made from the sulfonated aliphatic-aromatic copolyesters can be used to make shaped articles, such as sheets, thermoformed containers, and coatings for, for example, films and other substrates. The sulfonated aliphatic-aromatic copolyesters are produced from a mixture of aromatic dicarboxylic acids, aliphatic dicarboxylic acids, certain glycols, and components containing alkali metal or alkaline earth metal sulfonate groups, such as a metal 5-sulfoisophthalic acid derivative.