An accurate viscosity (dynamic viscosity) model is developed for aqueous alkali-chloride solutions of the binary systems, LiCl-H 2 O, NaCl-H 2 O, and KCl-H 2 O, from 273 K to 623 K, and from 1 bar to 1,000 bar and up to high ionic strength. The valid ionic strengths for the LiCl-H 2 O, NaCl-H 2 O, and KCl-H 2 O systems are 0 to 16.7 mol · kg −1 , 0 to 6mol · kg −1 , and 0 to 4.5 mol · kg −1 , respectively. Comparison of the model with about 4,150 experimental data points concludes that the average absolute viscosity deviation from experimental data in the above range is within or about 1 % for the LiCl-H 2 O, NaCl-H 2 O, and KCl-H 2 O mixtures, indicating the model is of experimental accuracy. With a simple mixing rule, this model can be extrapolated to predict the viscosity of ternary aqueous alkali-chloride solutions, making it useful in reservoir fluid flow simulation. A computer code is developed for this model and can be obtained from the author: (maoshide@cugb.edu.cn).