A homologous series of new surface-active N,N-di-n-alkyl-substituted amides derived from delta-D-gluconolactone and alpha-D-glucoheptonic-gamma-lactone were synthesized. The adsorption isotherms of their surface-chemically pure solutions were measured and evaluated to obtain the adsorption parameters of standard free energy of adsorption (DeltaG(ad)(0)), surface excess (Gamma(infinity)), cross-sectional area of the adsorbed surfactant molecule (A(min)), and surface interaction parameter (H-s). The surfactants possess comparatively low solubilities and do not form micelles at room temperature. This behavior is opposite to that of the other types of sugar surfactants showing excellent solubility and a strong tendency to association/micellization. The derivatives of gluconamide reveal surface activity slightly higher than that of the derivatives of glucoheptonamide, especially for long alkyl chains (n(C) > 4). An increase in A(min) of about 6 Angstrom(2)/molecule for the gluconic series is observed. (C) 2003 Elsevier Inc. All rights reserved.