Sloshing of cryogenic liquid propellants in launch vehicle tanks creates unwanted thermodynamic side-effects such as pressure changes in the tank.The goal of this PhD research was to develop a practical engineering model which is able to describe the influence of the sloshing of a cryogenic liquid on the heat and mass transfer and the associated temperature and pressure.The pressure changes caused by sloshing were investigated experimentally and numerically. Using the experimental and numerical results, a one dimensional (1D) engineering model was developed which is able to describe the experimental results.