The excess molar volume V-E, viscosity deviation Delta eta excess viscosity eta(E), and excess Gibbs energy of activation Delta G*(E) of viscous flow have been investigated from the density rho and viscosity eta measurements of eight binary mixtures of butylamine with ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol and decanol over the entire range of mole fractions at 303.15 and 313.15 K. The viscosity data have been correlated with the equations of Grunberg and Nissan [L. Grunberg, A.H. Nissan, Nature 164 (1949) 799-800], Tamura and Kurata [M. Tamura, M. Kurata, Bull. Chem. Sec. Jpn. 25 (1952) 32-37], Hind et al. [R.K. Hind, E. McLaughlin, A.R. Ubbelohde, Trans. Faraday Sec. 56 (1960) 328-334], Katti and Chaudhri [P.K. Katti, M.M. Chaudhri, J. Chem. Eng. Data 9 (1964) 442-443], McAllister [R.A. McAllister, AIChE J. 6 (1960) 427-431], Heric [E.L. Heric, J. Chem. Eng. Data 11 (1966) 66-68], and of Auslaender [G. Auslaender, Br. Chem. Eng. 10 (1965) 196]. The systems studied exhibit very strong cross association through strong O-H ... N bonding between -OH and -NH2 groups. As a consequence of this strong intermolecular association, all eight systems have very large negative V-E. Except butylamine + ethanol mixture, the magnitude of negative deviations in viscosity increases with chain length of alkanol.