The conductance data of trimethylsulfonium halides (bromide and iodide) in methanol at different temperatures (25, 30, 35 and 40°C) are presented. Results were construed by applying the Fuoss-Onsager equation to determine the characteristic parameters: equivalent conductance at infinite dilution Λo, association constant KA, the distance of closest approach of ions å. After calculation of the electrostatic Stokes' radii (R+ and R-), their sum is likened to å value. Thermodynamic functions such Gibbs free energy change ΔGo, enthalpy change ΔHo, change in entropy ΔSo and the activation energy (ΔEs) were estimated.