Relative static permittivity of the binary mixtures of amides (formamide (FA), N-methylformamide (NMF), N,N-dimethylformamide (DMF) and N,N-dimethylacetamide (DMA)) with alcohols (ethyl alcohol (EA) and ethylene glycol (EG)) over the entire composition range have been investigated at 1 MHz and 30 degrees C. The concentration-dependent relative permittivity increment and the excess permittivity of these binary mixtures reveal that the strength of heterogeneous H-bonded molecular interactions, the dipolar ordering and the molar ratio of stable adduct of amides with EA and EC are influenced by number of hydroxyl groups of the alcohol molecules and the type of substitution in amide molecules. (C) 2010 Elsevier B.V. All rights reserved.