The development of the temperature field in hydrogen tanks during the filling process has been investigated with Computational Fluid Dynamics (CFD). Measurements from experiments undertaken at the JRC GasTef facility have been used to develop and validate the CFD modelling approach. By means of the CFD calculations, the effect of injector direction on the temperature distribution has been analysed. It has been found that the dynamics of the temperature field, including the development of potentially detrimental phenomena like thermal stratification and temperature inhomogeneity e.g. hot spots, can be significantly affected by the injector orientation.