The conductances of lanthanum, neodymium, samarium, and yttrium hexacyanocobaltates(III) were measured in dioxane-water mixtures at 25 deg . All measurements were made in the concentration range below 0.002 molar. Dissociation constants for these 3-3 electrolytes are calculated by the method of Shedlovsky (K is approximately 10/sup -4/). Ion-pair size parameters are calculated by Bjerrum's method. Although Walden's rule is obeyed, the of the solvent mixture for a given salt, indicating lack of adherence to the electrostatic Bjerrum model. Yttrium cobalticyanide gives results somewhat at odds with the other three salts. (auth)