Data for the electrical conductivity (at 298.15 K), density, and viscosity [both at (278.15, 288.15, 298.15, 308.15, and 318.15) K] of aqueous solutions of choline chloride (ChCl) and chloro-choline chloride (Cl-ChCl) are reported for solute molalities m less than or similar to 2.0 mol.kg(-1) (ChCl) and less than or similar to 2.1 mol.kg(-1) (Cl-ChCl), respectively. From the densities apparent molar volumes were calculated, and the limiting partial molar volumes and Hepler's constants of ChCl(aq) and Cl-ChCl(aq) were evaluated. From the viscosities Arrhenius activation energies of viscous flow were determined. While apparent molar volumes suggest at best weak ion pairing for ChCl(aq) and Cl-ChCl(aq), the Walden product obtained for 25 degrees C hints at significant ion-ion interactions and/or changes in ion hydration with increasing concentration.