Rocket propellants are subjected to extreme thermodynamic conditions in high-performance liquid rocket engines, with temperatures in excess of 700 K and pressures nearing 100 MPa. Knowledge of the fuel viscosity is crucial for modeling the performance of liquid rocket engines utilizing rocket grade kerosene rocket propellant 1 (RP-1) or RP-2. The present study reports the viscosity of two RP-2 fuel samples at temperatures from 298 to 573 K and pressures up to 100 MPa. A high-temperature, high-pressure (HTHP), variable-volume, close-clearance, windowed, rolling-ball viscometer is used to measure the viscosity based on terminal velocity and RP-2 density. To facilitate the use of the RP-2 viscosity data with computational fluid dynamics (CFD) and other analytical models, these data are modeled with the free volume theory (FVT), with an empirical temperature/pressure-dependent correlation and with a modified form of the Vogel-Fulcher-Tammann (VFT) equation.