A thermoplastic molding composition comprising a linear (co)polyformal is disclosed. The (co)polyformal corresponds to formulae (Ia) or (Ib), ##STR00001## in which A independently denotes hydrogen or phenyl, --O-D-O-- and --O-E-O-- independently denote a diphenolate residue, in which -E- and -D- independently denote an aromatic radical having 6 to 40 C atoms, wherein at least one of --O-D-O-- and --O-E-O-- denotes 1,1-bis(4-hydroxyphenyl)cyclohexane residue. The composition is characterized in its restricted water absorption. Also disclosed is a process for the preparation of the composition.