The densities and viscosities of electronic grade phosphoric acid (EGPA) aqueous solutions with the mass fraction of H(3)PO(4) in the range of (78.7 to 90.2) % and temperatures from (283.15 to 313.15) K were measured. The densities range from (1.606 to 1.758) g.cm(-3) with the mass fraction in the range of (78.7 to 90.2) To under experimental temperature. The viscosities range from (14.63 to 134.56) mPa.s with the mass fraction in the range of (78.7 to 90.2) % under experimental temperature. It is found that the measured densities and viscosities are well-correlated with the temperature and mass fraction of H(3)PO(4) and are fitted to the regression equations. The thermal conductivities of EGPA coarse crystal (mixture of H(3)PO(4)center dot 0.5H(2)O crystal and phosphoric acid aqueous solution) with the initial mass fraction of H(3)PO(4) in the range of (84.2 to 90) % and temperatures from (280.15 to 298.15) K were measured by the cooling rate of 2 K.h(-1) with a total cooling of (3 to 4) K under the initial temperature, which simulated the operation curve in industrial application. The result shows that the thermal conductivity under this condition increases obviously when the temperature rises. The thermal conductivity decreases when the initial mass fraction of H(3)PO(4) increases.