Composition dependence of deviation in viscosities for the binary mixtures ofethyleneglycol monomethyl ether, diethyleneglycol monomethyl ether, diethyleneglycol monoethyl ether, diethyleneglycol monobutyl ether, triethyleneglycol monomethyl ether, diethyleneglycol diethyl ether and diethyleneglycol dibutyl ether, all with propyl amine. From the data, deviations in viscosities for viscous flow have been calculated. These calculations are fitted to various equations to estimate the binary coefficients. The results for Dh and in Dh are discussed on the basis of molecular interaction between the components of the mixtures.The results of Dh are discussed on the basis of molecular interaction between the components of the mixtures. The aim of this work is to provide a set of values for the characterization of the molecular interactions of these mixtures and to examine effect of the enlargement of –CH2– unit in branched ether.