Abstract: A process for the preparation of a linear tertiary aliphatic carboxyl functional polyester resin by reactinga) at least one compound A' comprising one monofunctional primary- or secondary hydroxyl group and/or at least one compound A" comprising one primary- or secondary hydroxyl group and one tertiary aliphatic carboxyl group andb) at least one aromatic or cycloaliphatic dicarboxylic acid compound B comprising two aromatic- or secondary aliphatic carboxyl groups or the anhydride thereof andc) at least one diol compound C comprising two aliphatic hydroxyl groups which may each independently be a primary or a secondary hydroxyl group andd) at least one dihydroxymonocarboxylic acid compound D comprising a tertiary aliphatic carboxyl group and two aliphatic hydroxyl groups, which may each independently be primary or secondary hydroxyl,the molar ratio of compounds A':A":B:C:D being M:N:X+Y+1:X:Y,wherein M+N=2X ranges from 2 to 8 andY ranges from 2-N to 8,at a temperature of from 100.degree. to 240.degree. C.