Viscosities for binary liquid mixtures of butylamine with benzene, toluene and isomeric xylenes have been measured at 303.15 K. Excess viscosity data have been obtained. The values of nEare negative over entire composition range. This may be attributed to the dissociation of self associated butylamine by the aromatic hydrocarbons. Further, the study has been extended to investigate intermolecular interactions in terms of excess free energy of mixing, strength of interaction parameter and interaction energy between the components.