In this work, we present densities and viscosities of aqueous solutions of sodium and potassium chlorate from (288.15 to 318.15) K at molalities from (0.1 to 1) and (0.01 to 0.5) for the aqueous solutions of sodium and potassium chlorate, respectively. Also, densities and viscosities of these aqueous solutions of sodium and potassium chlorate + methanol are measured from (288.15 to 318.15) K at concentration from (0.1 to 1, 0.1 to 0.3) m, respectively. Densities are from a vibrating tube densimeter and viscosities are from a rolling ball microviscosimeter. Ternary mixtures are prepared by adding (1 to 20)% volume of methanol to the aqueous solutions. Apparent molar volumes are calculated from the density measurements. Apparent molar volumes have been correlated using an extended Redlich-Rosenfeld-Meyer equation. The values of the parameters indicate that a stronger interaction of solvent ions occurs in the potassium chlorate solution than in the sodium chlorate aqueous solutions. The equation correlates the data within an average absolute percentage deviation of 3.7%. Limiting apparent molar volumes for the sodium and potassium chlorate aqueous solution from this work agree within 1.9 cm(3)/mol with the literature values. Solutions of potassium chlorate show an iso-viscosity behavior at the temperatures and concentrations considered in this work. Also, the Dole-Jones equation correlates the viscosity data within an average absolute percentage deviation of 0.29%.