AbstractThe substitution parameters, molar substitution (MS) and degree of substitution (DS) for commercial O‐(2‐hydroxyethyl) derivatives (HES) of starch have been determined by measuring the relative amounts of glucose and its O‐(2‐hydroxyethyl) derivatives in hydrolysates of HES. The monomers in the hydrolysate were estimated by conversion to per‐O‐ethylated alditols which were analysed by gas chromatography. The identity of the monosubstituted derivatives was confirmed by their mass spectra and by synthesis of model compounds. Disubstituted monomers were identified by their mass spectra while trisubstituted components were not separated.