The excess molar volume V-E, the viscosity deviation Delta eta and the excess Gibbs energy of activation DeltaG*(E) of viscous flow have been investigated from density and viscosity measurements of 15 mixtures of ethanol, propanol. butanol, pentanol, heptanol, octanol and decanol with di-n-propylamine, and di-n-butylamine, and of hexanol with di-n-butylamine over the entire range of mole fractions at 303.15 and 313.15 K. The VE of all the systems are very large negative. Except for the ethanol with di-n-propylamine and di-n-butylamine mixtures, the magnitude of negative deviations in viscosity increases with chain length of alkanol. The results have been explained considering mixed association of alkanol with diamine through O-H . . .N bond. The viscosity data have been correlated with the equations of Grunberg and Nissan, Tamura and Kurata, Hind, McLaughlin and Ubbelohde, Katti and Chaudhri, McAllister, Heric, and of Auslaender.