Excess enthalpies of binary mixtures between each of {CH3(CH2)(n)CN (n = 5-12)} and methyl methylthiomethyl sulfoxide or dimethyl sulfoxide have been determined at 298.15 K. All mixtures show positive enthalpy changes over the whole range of mote fractions. Excess enthalpies of the mixtures of nitriles increased with increasing size of the aliphatic groups. The increments of dipole interaction terms of mu(1)(2)mu(2)(2)(r(1) + r(2))(-6) on excess partial molar enthalpies at infinite dilution showed different behavior on the border of pentanenitrile.