Molecular thermochemical properties (heats of formation and atomization) of diverse functional acyclic compounds have been correlated with TAU indices and the relations have been compared to those involving molecular negentropy and first order valence molecular connectivity indices to unravel the diagnostic feature of the TAU scheme and to explore the relative suitability of the scheme in describing physicochemical parameters. For both the properties it was found that TAU relations could satisfactorily explain the variances of the thermochemical parameters and the relations were comparable to those involving molecular negentropy and molecular connectivity. Moreover, specific contributions of functionality, branchedness, shape and size factors to the thermochemical properties could be found from the relations involving TAU parameters.