The excess molar volume TIE, viscosity deviation Delta eta, and excess Gibbs energy of activation Delta G*(E) of viscous flow have been investigatedftom the density p and viscosity eta measurements of four binary mixtures of methanol and ethanol with triethylamine and tri-n-butylamine over the entire range of mole tractions at 303.15, 313.15, and 323.15 K The viscosity data have been correlated with the equations of Grunberg and Nissan, Hind, McLaughlin, and Ubbelohde, Tamura and Kurata, and McAllister. The systems studied exhibit very strong cross association through strong O-H... N bonding between -OH and -N < groups. As a consequence of this strong intermolecular association, all four systems have very large negative V-E. The V-E of the studied mixtures is consistently described by the ERAS model. The values of cross association constants K-AB illustrate the fact that cross-associates are more pronounced in a mixture of a short-chain tertiary arm. ne.