The conductance of s-acetylthiocholine halides and perchlorate has been measured in acetonitrile at 40°C.The data were analyzed using the Fuoss-Onsager equation for 1:1 associated electrolytes and the characteristic functions, Λ◦ (equivalent conductance at infinite dilution), a◦ [contact distance of approach (solvation)] and KA (association constant) were computed. KA values were analyzed on the basis of the solvent separated-ion pair model. The electrostatic Stokes' radii (R++ R-) were calculated and their sum was compared with the value of a° confirming the above model.