Johnson-Cook (JC) high-temperature strength material models have been widely used in finite-element analysis (FEA) to solve variety of hot rolling problems. Herein, the temperature- and strain rate-related parameters of JC model are experimentally calibrated for eight different steel grades including SAE 1018 and SAE 1045, structural steels (ASTM A572-60, ASTM A690, and ASTM A992), two V-modified 1535/45 grades, and one automotive advanced high-strength steel grade. Experimental data are obtained from tensile tests performed at strain rates from 0.001 to 20 s-1 and at temperatures between 900 and 1200 °C. A genetic algorithm approach is used to determine JC model parameters for different steel chemistries and to calculate the rolling pressure for a simple flat rolling process using both a common analytical formulation and a finite-element model (FEM). A model for the effects of steel chemistry on the JC model parameters is also discussed.