In this research enthalpy balance analysis of the EN AW 5182 aluminium alloys during entire process path of sheet production was made, whereas samples after every step of sheet production process path were obtained. Using Thermo-Calc computer program thermodynamic simulation of equilibrium and nonequilibrium solidification was made. Differential scanning calorimetry was made on every sample, whereas the melting characteristic temperatures and the melting enthalpies from the results were obtained. Optical microscopy and scanning electron microscope with energy-dispersive X-ray spectroscopy were used to analyse microstructure and microstructural components. It was found that each step of the process, involving different processing temperatures and deformation, has a significant effect on the reaction/melting enthalpy and cannot be uniquely described. Homogenization reduces and intermediate annealing of the hardened sheet increases the melting enthalpy. Hot rolling has a significant effect on the melting enthalpy, while cold rolling has only a minor effect.