Excess parameters like excess acoustic impedance (Z E), excess internal pressure (π i E) and excess enthalpy (H E) have been calculated from measured densities (ρ), sound speed (u), and viscosities (η) of a binary mixture of diethylamine and 1-decanol at (293, 303, and 313) K over the entire range of compositions. Further, these excess parameters are fitted into the Redlich–Kister polynomial equation to find smoothing coefficients and standard error. Different theoretical models of sound speed are also applied to experimental sound speed to find the best fit theory for the system under investigation.