Molar excess volumes, (VE) and the ultrasonic sound velocity (U) of binary mixtures of triethylamine with ethylbenzene, chlorobenzene, bromobenzene and nitrobenzene have been measured at 308.15 K. The speed of sound data were used to compute isentropic compressibilities (ΔKS) and deviation in isentropic compressibilities (ΔKS).VEvalues and ΔKSvalues are negative in all the systems, over the entire range of composition. The results are interpreted on the basis of intermolecular interactions between unlike molecules.