An in-depth analysis including both simulation and experimental characterization of Resistive RAMs (RRAMs) with dielectric stacks composed of two layers of HfO2 and Al2O3 stacked in different order is presented. The simulator, that includes the electrodes in the simulation domain, solves the 3D heat equation and calculates the device current. The results are employed to analyze thermal effects in bilayer HfO2 and Al2O3-based RRAMs with electrodes of Ni and Si-n+ during resistive switching (RS) operation. According to our simulations and the experimental data, the narrow part of the conductive filaments (CF) is formed in the HfO2 layer in all the cases and, therefore, no important differences are found in terms of reset voltage if the oxide stack order is changed with respect to the electrodes. This result is attributed to the fact that the heat flux in the Al2O3 is higher than